So i'm not sure weher i should consider this an SR4 or 5 question, because i'll be pointing out data from SR4, the SR wiki, AND SR5...
Regeants in SR5 are basically a converted equivalent of power of a DRAM of orichalcum. A dram, being a standard 1.77 grams, and cost (20) nuyen i think, dont have my book but it's close to that.)
SO, we can extrapolate that 1.77 gram's worth of orichalcum is worth 20 nuyen.
The SR wiki says a single unit of orichalcum is worth 88k (i think it was 50 in Arsenal, but again, from memory) for 10 GRAMS, which is a unit.
So making a katana blade out of orichalcum, at about 1kg the blade, would either cost you 11.7k if you use regeant rules, OR 8.8 MILLIONS if using the wiki.
Which would it be? Am i missing something, like purity of orichalcum, downpricing due to Haley's Comet temporarily making orichalcum easier to gather, some consistency goof in the rules? Figure i'd point it out, if anything, it might be taken under advisement for SR5 supplements and the equivalent price of Orichalcum. It's a very, very minor thing, but if it can at some point save a GM from the headache caused by an overly enterprising rule lawyer PC, then my job'll be done
Even with downpricing, i cant believe that in a few years, an 8 million dollar weapon would suddenly be 752 times cheaper