I wouldn't bother with anything nonstick used from a thrift store. Almost invariably, whatever has been "donated" has had the effective nonstick coating worn off.
For a budget pan, try a TJX off-price store. (TJX is a corporate structure - HomeGoods, TJ Maxx and Marshall's, with . One set of buyers serves all three named chains and with the same distribution network for all the chains). Look for the heaviest Calphalon pan they have - preferably a Unison pan. I've usually been able to find something.
Budget and non stick kind of precludes a recommendation. It comes down to what deal you can find. Costo often has decent deals in non stick. If you have one of their business centers around, they have some coomercial culinary non stick that I think are good deals from Clipper. The silicone grip slips right off for oven use.