As far as guns go.... You get what you pay for really, but on the rare occasion you get a real gem. Example. I bought a Norinco 9mm Tokerev for very very little. It was alright, but jammed a lot. (like 5 rounds out of 50) consistantly.
However I bought an ithica model 37 12gauge for $100 out of my gun club newsletter classified and its fantasic, in fact, flawless (so far) but I have put over 800 rounds through it since.
Research research research what you need it for. Then hunt for deals