Impact Guns currently has a deal to buy a walther p22 for 500 bucks. This includes the gun, threaded barrel, and silencer. This is about as low as I have seen them online thus far. Its a fun toy to have. Remember this does not include the 200 dollars to the feds.

http://www.impactguns.com/store/product2296.html

Thus its going to be 700 bucks without tax to get a silenced .22 handgun. Cheers!!!