Minesota
Young Gun, since you list your location as Minnesota, you will be limited to C+R machineguns, of original manuf. not re-productions so you will basically be paying top dollar for top grade expensive guns.
A M16 will cost you around $17K, your lowest dollar gun available to you would be something like a S&W 76, or Sten at around $6k, A Reising in 45acp could be had for 4.5K or a bit less. Similar money for a 30 Carbine.
You are not going to be allowed a silencer, but you can make semi auto Short Rifle clones of modern weapons.
If you get your C+R license from the ATF then you can purchase C+R machineguns direct from out of state dealer without going through an in state MN dealer and paying them the fee.