Colecovisions are pretty easy to fix. Most failures are dirty cartridge contacts, bad power supplies, faulty power switches, cracked solder joints on the power supply connector, cracked solder joints at the cartridge slot, and bad RAM. Also, there are some chips that drive the controller ports that like to fail - so if you have a dead port, look into it. I think it's just a buffer chip, but I don't remember off the top of my head.
Not a particularly well made console, the Coleco. And nothing a well-versed arcade geek can't fix. And you might want to look into rust-proofing... these Colecos will rust up on you like that! <grin>
That said, they do seem to be harder to find than Atari systems. The weird thing is that I live in New York, not 30 miles from Amsterdam where the big Coleco plant was. And yet even I don't see Coleco systems very often. They probably all broke in the mid 80's and got thrown out...
That said, $150 seems a bit steep - only buy it if you really do want it, and that game it comes with is actually very rare.
EDIT: Just reread the post and saw what game you were talking about. BC's Quest for Tires isn't very rare - even I have that one. Way, way too high.
-Ian