If you have more information (model number on sticker possibly), then that would be helpful. However, it does appear to be a three cylinder, so it probably kicks out a decent amount of air. Most likely it will be enough to run any air tool that you want since any similar model I found kicks out about double the requirement for an impact or about 15 CFM.
You will want to check that:
-There is oil in the system (to make sure it wasn't run dry),
-The tank can hold its air pressure
-It can run without making any strange knocking noises or other problems.
-The regulator will adjust pressure accordingly (crank it up to 90, and then adjust to 50 and listen for the air to release and then stop)
-The wiring looks good, and there isn't any hack job repairs
You may want to wait until some other guys on here chime in, but if it works good I think that if you could get it for around 150 that would be a decent deal. $100 would be great.