I bought a 40 dollar Craftsman about 6 years ago... Initially, I was using it to grind fork stops and lugs off of motorcycle frames, so it got the crap wrung out of it running top speed all the time and it still going strong. When I started building my first cab, I thought it'd be very useful, but that turned out not to be the case. I think the only thing I used it for was to notch away some metal in the base of my metal control panel to make a trackball fit.
As an occasional use tool, I don't think you need to go high end.