FN P90 -- $2350

The FN P90 is a nice gun, and for one reason. Where as most guns have a 30-round clip or smaller, this gun has a 50-round clip. This means that when you opponent runs out, you will have 20 rounds left, so you can run right up to them without fear of retaliation. You can have an additional 100 rounds of 5.7mm ammo with this sub-machine gun, and it cannot be used by terrorists on assassination maps. Plenty of ammo, moderate damage, and a fast rate of fire make this the best sub-machine gun choice, for a bit more money.