Mini-14 found disassembled at a garage sale, $35.
Yep I'm still bragging about that one.
My tricks to a good deal are 1, never buy new. 2, know what a good bore looks like. 3, let everybody and their brother know what you are looking for and you're paying cash. 4, don't be in a rush. 5, hit estate and garage sales that feature sporting goods. 6, don't pass up good deals on anything that could be tradable/saleable even if you don't want it, it will be valuable later. 7, Network, network, network!, When I'm looking for something EVERYBODY knows it. 8, ALWAYS remember that this is a WANT and NOT a NEED. Keep this attitude when buying anything. I sold cars once and a needy buyer is known as a 'laydown'.
Follow my advice and you'll get your deal, most likely a good one. I've been doing this for over 40 yrs.