The lowest price I've ever paid for a piece was $280 for a Ruger LCP.
I've seen Mark II/IIIs for the sub $300 range used and that is a very good deal if you can verify they are undamaged.
I purchased a used .17HMR Rimfire rifle with scope for $300 and a used CZ P-01 for $380.
XD Svc. .40 S&W, Trijicon Night Sights, Powder River Match Trigger, Don's Stainless Guide Rod 22# spring, XDm slide stop
XDm 9mm, Springer Match Trigger, X-treme Grip, Don's Stainless Guide Rod 16# spring
And more from Beretta, Benelli, CZ, Kimber, Rock River, Ruger, and Savage.