There are 3 thrift shops I regularly visit. Salvation Army (3 locations within 50 miles) and Goodwill (7 within 50 miles) are all major source of relics I buy. Normally they do not haggle and I've never tried.
The third one is a local charity shop just a few miles away, almost everything is 25 cents (books and mags are 10 cents). It's almost silly to try and haggle for a few more cents. In fact I left more than what I took out, probably over $1,000 worth of old clothes, commercial VHS tapes, audio tapes, obsolete but working computer stuff, and more. It's also my favorite source of surprises, like a working Zebra thermal printer for 25 cents (they still go over $100 working on eBay) all I needed was a roll of 4x6 (any size from 1" to 4" wide, and 1" to 6" long works) labels and I could print out address labels or full postage paid label if I can.