I would love to own a full auto SMG 9mm or anything in 7.62X39. What firearms are the least expensive? I know there are certain NFA fees involved, so I want to keep my weopon costs down. I chose those 2 calibers because of their low cost.
FYI, if you get a Cobray M11/9 subgun, you can buy a .22LR upper for it and shoot .22LRs all day long. That makes it among the cheapest to buy and cheapest to shoot.
The "NFA Fee involved" ($200) is completely insignificant to the amount you will spend on the weapon. Plain old sales tax is more than the NFA tax stamp.
Another piece of advice is buy what you want. If you want an Uzi, buy one. Same with a M16 or MP5. If you want an M16 and buy a M11/9, you won't be happy.