The cabinet blasters are a nice tool. The abrasive you use will dictate a number of things so be sure to match it to the job and equipment. I like glass beads the best, they fracture on impact and scour the surface, aluminum oxide will tend to partially imbed itself into the part and I don't find that desireable, just my preference. They are heavy consumers of air. I have been fortunate enough to have access to shops with rotary compressors. Every cabinet I have used, regardless of make or model or vacuum attachment has left media on the floor and dust in the air. Here is something to keep in mind, you may want to move it outside to use it because it will leave a media residue on everything in the vicinity no matter how careful you are and I know I don't want to get my tractor dirty, you may not either. /forums/images/graemlins/grin.gif
There is little chance of justifying one, financially that is, to only have occasional use for it, so consider taking the parts to an outside service, but if you are the type of person who likes doing it all yourself, buy one to fit your needs and capabilities, you'll like it. Better yet use a friends for free.
Best of luck,
Martin