i got the same problem with 'buddies' leaving shit here...
from 2 tractor trailers, cars, motors =even boxes of dishes...... if it's not my stuff-i don't even think about selling it & i never throw shit away. (recycle or sell)
untill... i stub my toe on it or can't find a place to put my own stuff.
~ if i tell the mf's to come get it- and they don't- that makes it MY STUFF (unless said friend has good excuse not to get it or no place for it yet- but if they say "yeah, i'll be there saturday" and don't show up- f 'them-....). no lawyers, no cops.... i proudly list it on craigslist and send them the link- and i DON'T give them shit if they haven't been straight with me...
you've done nothing wrong- f the x-friend. 3 years is just too long, and looks like you did your part to make it right for a long time... what the hell was he doing for 3 years anyway? school? he probably got wind of the stereo being sold from someone else (another 'good' buddy) then wanted some fast cash at your expense
don't give him anything since he's being a dick about it.
what else did he leave? any da or civic parts?-hahaha