Downs: Prices go skyrocket...and even the worst one will cost around 40-50million and the best ones will go over 100-150mill.
Ups: Actually this increase of rarity can give some reason why these guns can be much better from some aspects compared to their civvi/military/(other stuff) counterparts.
This randomisation maybe can give the chance to everyone to get the so wanted code gun for free with a lost of luck.