Over here there are only few thrift stores, but more goodwill shops. Often something inbetween: people in need of a home financing their hostel.
Typically the offer of cameras is very limited and prices are higher than on my favourite flea-markets. So I only pay them a visit when I pass them anyway, or when there is a once-years photo stuff offer where they put a lot of stuff on sale.
I guess my best deal at such a shop was a Osram Dunco 10 ligh,t originally packed, for a few euros.