I saw one of those GMC polishers in Lowe's today, but for way more than $39. It was marked at $74.95, and for that price I would just buy a PC. Also, the one I saw looked nothing like the SA515 or 516 that you describe. It was similar in looks to the PC. Too bad my local Lowe's doesn't carry those though. Probably want to steer you toward the GMC for some reason.