I believe that you need a class 3 license to purchase a supressor??
No license required... only a Tax Stamp... at least here in Florida.
I was in a local gun shop the other day and they had a varierty of supressors on display for sale... the catch is they usually make you buy the handgun and supressor together as a package... and they aren't cheap.
Some other interesting benefits of the Class III Stamp here in Florida are, you can also legally own full auto rifles (AK-47s, UZIs, Mac-10s), sawed-off shot-guns (entry guns) and for the Daily Double, you can even get a UZI or Mac-10 with a supressor!