Right! So, some detailed bits.
The simplest mechanic for this particular bit of boosting would be to simply take teh Karma cost of raising an attribute from the primary chart, convert it to nuyen, and call it a day. Thus, raising a Strength from 1 to 2, which costs 10 Karma, would cost 20,000 Nuyen, while raising a 4 to a 5, normally 25 Karma, would cost 50,000 Nuyen.
This leaves out the secondary cost of Essence, of course, and leaves out the assorted minor penalties that come with cyber (social stuff, harder to sneak past sensors, and so on) ... so, you need some kind of cost break as a trade-off. But how much? How much is that loss of Essence worth, and furthermore, when you have something like Muscle Replacement that bumps *two* attributes at once, how do you determine the cost of that? SHould you split them into two separate bits of Cyber like you have for the Bioware versions? How does this hold up against legacy cyber?
So, a tricky question.
You also start to eyeball the concept of "What is teh cost of Essence loss?" ... in 1st edition, if you hit 0.0, you died. Beyond that, if you weren't magical, there was no difference between the Street Sam with 0.1 Essence, the Decker with 5.0, and the normal dude with 6.0 ... there were roleplaying hooks about emotional detatchment and cyber-psychosis, but mechanical apects for that didn't come around for a while. If you wanted to really crank it up, you could require every reduction in Essence to be offset with negative qualities ... mental, but also social or physical (Like immune system issues) , really showcase the inhuman aspects of cybernetics. Here we get to another bit of design theory ... woudl you keep the value flat, such as 10 Karma for each point of Essence lost, or would you use a sliding scale? You could reverse the main Karma chart, so that losing 1 Essence was worth 5 Karma, 2 was 15, 3 was 30, and so on, creating a very definitive side-effect for Essence loss.
If you went that route, you could ultimately make cybernetics *free*, since the cost was being paid in another way (required flaws!) ... but you also would have to look at the tradeoffs. If Muscle Replacement 2 was free in terms of cash, required you to take 15 points of flaws, but gave you let's say Agility form 4 to 6 (55 Karma) and Strength from 6 to 8 (75 Karma), then you'd be looking at a net gain of 105 Karma ... that's a no-brainer for most people.
So, we don't go there.
We also have to take into account Bioware... if we decide that, combined, Muslce Augmentation and Muscle Toner 1 should be 0.5 Essence, vs 1.0 for Muscle Replacement, but cost twice as much, then we have to look at things like Alpha quality ... if it doubles the price of cyber but does NOT give half off in Essence, then Bioware is flat-out better. If Bioware reaches levels of low-Essence cost that cyber can't (Even Delta grade doesn't get Muscle Replacement to the level of Aug + Tone) then Bio needs to cost more than a Delta-level of Replacement or, again, there's no real reason for the cyber. This is further complicated by the ultimate cap of "How much Karma would getting the same benefit cost?" ... if it's 40 Karma to buy +1 to each naturally, but 60 Karma (120,000 Nuyen) to buy it, and that comes with more negatives, then you've eliminated the need for the cyber entirely!
Lastly, there's an encouragement factor. (You'll see this later with Trolls) ... do you want Replacement to be priced at a level that eeryone will take Agility and STrength of 1, then boost it with bio/cyber due to how cheap it is, or do you want to encourage only those who already focus on those attributes to be investing in it while making it cheaper for low attributes to Karma it? (This is more of a lasso for powergaming, but it covers design as a whole... remember, one of the design goals is to make choice more difficult. Anything that's an obvious no-brainer is bad.)
So, let's say that you want to encourage focus. You further want to establish a 'break even' point, a place where cyber's shortcut starts to really look appealing. Since we're dealing with a core book, we also decide on simplicity... instead of using the Karma chart, we'll just use the traditional (Rating * Nuyen) rate for the cost, instead of an ever-increasing cost based on teh sliding scale.
Sitting down and testing some numbers, you can put that cutoff about anywhere, but for this discussion, we're going to use the move from 4 to 5, where you go from 'Well-trained human' to "Really dang impressive" ... this is where the "shortcut" of cyber belongs in the snapshot of this thread. Lower than that, you get better results the old fashioned way, while those who truly focus on, say, Strength, are already paying an execptional cost, so saving them a little more for concept is a nice lil' backpat. Since we know Bioware will be more expensive but cost more Nuyen, we use it for a base, then work the cost for Cyber for there.
So, moving from an attribute of 4 to 5 costs 25 Karma, or 50,000 Nuyen. Bioware is minimally invasive, and we decide on .25 Essence as a good starting point, and note that Bio is vastly more difficult to detect than cyber, so it doesn't need a big discount. We go with 10% off for now, making it cost 40K per Rating.
For Muscle Replacement, we know that we'llhave Alpha and Beta around, even if we don't know the cost multiplier yet. If it doubles the cost, and we set +1 Strength to 20K, we can see that it won't be low enough ... Cyber will have roughly twice the Essence cost, and if Alpha doubles the price but doesn't half teh Essence, it's no good. What if we quarter the price, to 10K? 10K is a mere 5 Karma, so you get a substantial boost at a discount, but the Essence cost is a bear. We see no need to change it from the traditional 0.5 level, which means Musle Replacement (1) will set you back 20,000 Nuyen and 1.0 Essence, vs the 80,000 Nuyen and 0.5 Essence of Bioware. This gives you some wiggle room for what you expect Alpha to be (double the cost, 80% of teh Essence) and Beta (Four times the cost, 70% of teh Essence) with the latter starting to give way to Bioware.
In the real world, Grade costs came way down. Teh final cost of Muscle Replacement and Augmentation/Toner isn't what I'm showing above, so, clearly there were more factors.
But, you start to see teh mechanical design and you get a starting point to go further with. You can make Bioware more appealing by lowering the Essence cost some, from 0.25 to 0.2, for instance. You can give CYberare a bit more of a price reduction, since it comes 'bundled' in a +1 AND +1 format, rather than just letting you buy "the good bonus" of Agility without Strength. You can fiddle with Aug/Toner prices to make it easier to get the less-valuable resource (Strength) and more expensive to get the 'good' one (Agility) ... Maybe you go with 40,000 for Toner, but only 30,000 for Augmentation. Maybe you make Strength more valuable as an attribute, to keep some better game balance, or make Agility somewhat worse for the same effect.
If you adjust the cut-off point up, from 4-5 to 5-6, you make Cyber more rare. If you move it down from 4-5 to 3-4, you make it more common. You can lower the cyber price more to make it even more appealing, or make the cost break for bio smaller to make it a harder choice... lots of fine-tuning can follow, once you settle on a basic philosophy and a core price point.
If we start with the idea that +1 Attribute is worth 25 Karma/50,000 Nuyen all by itself, just how much of a price break do you want to get for Bioware or CYberware? That's where the factors get interesting. That's also where you'll start to see a lot of arguements.
So, now it goes back to y'all ... how big of a reduction starts to feel fair, with this in mind? Would you have explored an alterante method (For example, the negative quality kickback based on Essence lost formula) instead, or would that be too big of a change and a simple Essence mechanic retained be superior? What sort of cost and benefit would you want to associate with STandard, Used, Alpha, Beta, and Deltaware? Would you need the 'Cap at Alpha' requirement, or would cost, and availability, modifiers be enough to keep things balanced?
It's a complicated dance, and we're still ultimately focused on just three Augmentations ... there are just all those echos to watch out for that are bouncing around from each decision.