It's a glitch (no products to buy), I had that problem before, and one day it was gone. I don't know why.
Yes, you can reverse engineer nanites you create, but they don't have as many processors as wild nanites. You can do either of these, or all 3, which won't cost you money :
- place nanite spawners ;
- clone nanites if you've got University and high science skill ;
- get twice as many processors from reverse engineered nanites with a mod (I can't give a link to the mod as I don't remember where I got it, and i can't find it on Google, but anyway I've got a mod for this).