You should be able to find a very nice hammer gun for under $3K. That puts you in the range for some American classics like Parkers and for some of the nicer modern European guns like the Bernardelli Italia or Italia Extra, or a Siace, or a Beretta/Mi Val. For half of your budget you could get a Bernardelli Brescia. You might even find a Brit hammer gun in good shape in your price range. The Bernardellis will happily shoot WallyWorld shells all day long. The Brit guns and the American classics should be fed lower pressure stuff.