They're about $ 7,000 each from your local FFL.
OTOH, drug dealers can probably afford them more easily than you or I, just as, ironically, Frank Nitti's boys could easily have afforded the $200 transfer tax on their Thompsons, proving that the Sullivan Act was mostly eyewash, and no substantial bar to gunsels' possession of submachineguns.
The real squeeze on criminals is their loss of civil rights, that felonizes their possession of firearms.