Derek, if you mean the semiautomatic clones then yes. If you mean the full automatic assault rifles, then yes. I'm not positive on the minimum age requirement, you'd have to check FL laws.
Expect to pay $3400 to $4200 for a semiautomatic Steyr AUG (depending on options and stock color), $700 to $2500 for a semiautomatic AR-15 (again, depending on options and whether it's pre or post-ban), and upwards of $8000 for an original semiautomatic FAMAS. I even saw a semi SIG-551 on the ad boards recently. Only $10,000.
For full auto specimens, Steyr AUG's fetch around $7000 to $8000, M-16's around $4000 to $8000 (depending on model), and I don't think there are any transferable FAMAS rifles out there. Pre and post dealer samples maybe, but they'll be super expensive too. Probably at least $10,000.
And yes, machine guns are available new in the box, if the original owner kept it that way. Remember, NO machine guns manufactured after May 1986 can be owned by civilians without an FFL (Federal Firearms License, equates to a dealer's license). That means unless you're a dealer, forget about owning a real HK UMP-45. Sorry.
Also remember though that the only part of the gun that's registered is the receiver. That means that if you shoot 120,000 rounds through your M-16, all you need is a new barrel (and maybe a few internal components) and you're good to go. Guns can be refinished and restored to look brand new. Some highly skilled manufacturers can even take a torch cut receiver and WELD IT BACK TOGETHER to form an operational firearm. Now THAT is a feat of engineering.
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