Burgie,
Avoid the oilless units. I have a cheap 2HP one for airing up tires and such - plug it in, charge it up (noisy as all hell) - put it in the bucket of the kubota and haul it across the acreage to air up a flat tire on an old truck that is about all it is good for.
The DeVilbiss unit from Sears takes a 50Amp 230V circuit to start it and does a fine job of keeping up with the blaster and my DA sander and pneumatic longboard sander. The pneumatic cut-off saw makes it work hard and it eventually needs a break to catch up.
I have a Dayton 2-stage industrial unit at work with a 3-phase 5HP Baldor 460V motor on it - no comparison on how much air that 5HP industrial unit puts out compared to the sears unit. But . . . for occational body work, blasting and general home use, the sears unit can be had for under a grand easy while the Dayton unit will set you back closer to three grand.
Sounds like you are asking all the right questions - I wouldn't hesitate to spend as much on the compressor as you are planning on spending on that blast cabinet - while the pain in the wallet will make you wince up front - you will not regret it down the road.
