I picked up a nice 1933 Weymann from eBay last Fall for around $200. It's got a tone ring, came with a case and is made in the USA.
Similar to what brewerpaul said, I put new tuners and a bridge on it (which cost about $50) and it's got a nice sound! Plus I got it from the original owner and he took good care of it over all these years.
There's nothing wrong with buying a newer 4 string tenor from a reliable vendor, but in the $300-500 range a lot of them will be made in China or Korea. Mind you that's a matter of personal preference where an instrument is made and whether that affects the quality or not.
But I do find if you can get something that's been well loved, it picks up character over the decades...it's kinda like rescuing a happy dog from a pound instead of shelling out big bucks for a pure bred with no personality.
My two cents, best of luck with your search!