That all caps post, it nearly killed me....
Seriously. Canisters at shops? To unrealistic. Either the rebels would rob you, the shapers would blow you up, the trokovites(forgot their spelling) would kill you, ect. ect. Also. That would defeat the purpose of canisters and make the game less enjoyable.
We also have to many ways to get exp as it is and canisters already give us upgrades in our skills, new spells and new creations. So I say no to having them also give exp.