I don't have any personal experience with them, but the 70ish greeter at the local Walmart has been riding a really inexpensive, off-brand scooter he bought at PepBoys, to work for three years.
He just recently bought a new, larger one (from a dealer, not from PepBoys), and I believe he said it was a Sunel, or something like that.
They seem to be knock-offs of other, better known brands, and the biggest problem seems to be with getting replacement parts (so I'm told).