I bought one of the Craftsman "oiless" design compressors several years ago. It was so LOUD that I took it back the next day. /forums/images/graemlins/eek.gif I've now got a 5HP, dual cylinder Sanborn compressor that uses a belt to drive the motor (most oiless designs seem to have the two directly coupled). I've been very happy with it.
At $300, you're pretty close to the low end of usefullness. You'll find that anything less than a 5 HP compressor will have you often waiting for the compressor to catch up with you. Due to the pumping losses here at 7,000 feet above sea level, I could even use a 6 HP now. The 5 HP worked great at sea level for everything except long die grinding sessions. But up here I find myself waiting on it more often that I would like. A larger storage tank can help with this, but eventually you'll still outrun the pump in some instances. Oh yeah, any compressor at this level will require a 220 volt power supply, so make sure that you have the proper electrical outlet handy. /forums/images/graemlins/thumb.gif
You'll need more tools than just the standard impact wrench. Also, the $39 impact wrenches suck at removing stuck nuts/bolts. They're OK for when you're first starting out, but after you get frustrated with having to use a breaker bar to loosen lug nuts, so that your impact wrench can then finish removing them, you'll want to step up to a good unit, like the ones from Ingersoll-Rand.
I use my 3/8's drive butterfly impact wrench at least as much as my full size 1/2-inch one. It's much smaller, fits into tight spaces, and works MUCH faster than my air ratchet. I've hardly even used the air ratchet since I bought the butterfly impact wrench. /forums/images/graemlins/cool.gif
