Keep looking, you will find one in your price range. A hammer gun with only iron sights can sometimes be a few dollars cheaper. If you require a scope, be sure the used gun comes with scope and the mounts. Fitting a scope on a driling can be very expensive.

You might want to check Bob Jones. He usually has a variety of guns in various price ranges: http://www.bobjonesguns.com/inventory.asp#DRILLINGS

You can get adapters that will allow you to shot 70mm 20ga from a 65mm 16g: http://www.drillinghotline.com/accessories.shtml

Pete

http://www.damascus-barrels.com/Movie.html