Yard sales and pawn shops would be the place to look.
You could also try contacting theflea here on VGCollect. He might have a few he's willing to part with.
I'll try contacting him, thanks!
And yeah, that's what I suggested to my friend as well. Even pawn shops can be a bit pricey sometimes, unfortunately, and (at least at my local pawn shop), the quality of the items is... less than desirable. xD