How much for a used 7D?
For that price range you are looking into, I would suggest such dealers like Amazon for used. I shop CL when I expect a better deal than going thru any main stream seller. Or opt for a brand new 60D. If the super AF is not a need for you (and the 60D has a great AF system), you can get brand new for $850 or so with the 60D. Good luck.
Darkness is the monster and your shutter is your sword, aperture your shield and iso your armor. Strike fast with your sword and defend well with your shield and hope your armor holds up.