Lots of folks buy old video games and resell them on EBay. You're actually doing something good; you're helping get the machine into the hands of a collector who will take care of it.
A couple of weeks ago I bought an Intellivision for $7. I took it home, hooked it up, and found it worked. I sold it on EBay for $25.
It's not something you're going to get rich on, but it is kind of a neat feeling to find something that was destined for the junk heap and instead sell it to someone who will play it and appreciate it.
Most video consoles are actually pretty hardy beasts: they have no moving parts and they were designed to be handled by kids so they can take a fair amount of punishment.
Generally 90% of all console problems are dirty contact or bad wiring connectors. Get out the old toothbrush or Q-tips with rubbing alcohol and get cleaning!
