I don't have these issues with my Goodwill. I'm talking the official Goodwill:
Cartridge games are $2-$5, depending on what it is (Atari goes on the $2 end, Nintendo on the $5 end, Sega in-between).
PS1, Dreamcast, & PC Games are $3.99 (they lump them in with CD pricing).
DVD-sized case disc-games are $4.99 (lumped in with DVD pricing).
Granted, there's often times I can't find much. But at the same time, I've really found some gems there like Chrono Cross, Rampage on SMS, Paper Mario Thousand-Year Door, Super Mario Kart & MK: Double-Dash, Arc the Lad, a freaking Commodore 64; just to name a few.
However, I haven't seen any cartridge games in a few months, now. I don't know if it's just because no one's donated them in that long, or if they just stopped carrying them. I have seen Sega Genesis and Atari 2600 systems, though.
I was just in the other day and picked up Star Wars: Dark Forces, a Dual-Shock Controller, and A Bug's Life all for PS1. Granted they're not the highest sought-after items, but you can't complain for a few bucks. And I got True Lies and First Blood on that trip.