A heads up, the machine I mentioned (see you PM) is a Rev5 NTSC. If you are considering an ACA500 at all, it is probably not the best choice for you.
No kidding, I've been, perhaps to passively, trying to source a Rev6, or better a Rev8 (A500+) for a year or so, and either miss them, or watch the prices sky-rocket beyond reason. Someday, perhaps, or give in and pay shipping from europe. One or the other.
Id have to say you are NOT going to find an A500+ in the usa they are very rare and with the Hoarders that abound its gonna be a tough one unless you are willing to pay!