Give them all this common minor fixer as a free contact; in this way, you are not penalizing them in any way and are also giving a little something for them. Having to pay for a resource you will not use is not cool.
About the fixer's commision, I usually consider this to be a deal made between Fixer and Johnson, and so the characters don't need to bother about that (and will usually don't know about that). Well, you are talking about how it usually works, and here I can only bring examples for the few games I played. If you take the missions, the fixer's cut is something that is never discussed, so it's implied that has already been dealt with or is not something the characters should concern themselves. The only game I played that one fixer directly intervened and asked the character directly for a fixer's fee there was some RP-reasons for that particular fixer try it - and yet, he would receive nothing more than the "unknown but pretty much high enough" fee for that particular job.