I stopped reselling my electronics and just give them away to whomever needs them - somehow, that's less depressing than knowing I bought something for $500 and now I sell it for $100 (and my stuff looks like new even after years of use).

Buying used smartphones, on the other hand, is great - you can get a G2X or a Dell Venue Pro (excellent Windows 7 phone) for under $300 easily, and it will work just as well as any other phone (especially the G2X with a custom ROM)...