The Goodwill in my area is pretty savvy when it comes to prices; they actually check eBay’s completed listings ergo finding a deal is tough. I did find Double Dragon for Game Gear for $2 though so I always look despite the usually high prices.
You are being very generous using the term 'savvy' for Goodwill. I would use other choice words that are not family friendly. They freely admit that they use ebay as a guide. Thrift store buying is so convoluded now. Arrgghh!