Originally Posted by
eladro
The value of the bike right now is the ~$80 I've spent on the new tires, tubes, brake pads and having the shop look at the drivetrain. So if by putting another $150 into it I can get a bike that rides better than a $500+ model, I'd be very happy with it. $250 for a bike with good tires and a high end (for a regular bike) drivetrain doesn't sound like a bad deal at all. If I ride it 3 miles a day for 8 months a year it's already worth it (this is a minimum, an underestimate, not even including non-commute rides).
From what I'm looking at now:
New wheel/hub: $50
New cassette: $30
New shifters + derailleurs: $50-80
New chain: $30
How about this:
New 7 speed cassette: $20
New 7 speed chain: $15
New 7 speed shifters: <$30
Total: $65. The derailers are probably fine, although they can wear out eventually. Just because it's not shifting now does not mean they're broken. It just means that the cables are completely trashed or they're out of adjustment. As long as the pivots still move smoothly (with no cables attached) they are probably fine.
I'm not sure where you can get a decent new rear wheel for $50, but if your old wheel is still true I would continue using it. It will be at least as good as any new $50 wheel.