Around here, there's basically nothing left that's a "used computer shop". There are a couple places that will apparently buy big lots of surplus .gov and .edu P4 machines, install bootleg WinXP, and sell them for 99 dollars for people who just need a throwaway PC, but nothing like in the old days of "I need a motherboard, here are the used 386 ones, 486 ones, and Socket 7 ones"
I'd heard many charity shops got spooked on selling computers after some got hassled by the BSA because they couldn't account for the software on the machines.