There are two companies that manufacture these mini-lathes: SEIG and Real Bull. Look at the saddle. The SIEG lathes have an H shaped saddle and the Real Bull have a rectangular. Also the Real Bull lathes have wipers on the saddle for the ways as well. Some, not all parts are interchangeable. There are also some of the Real Bull lathes that come with a 4 in chuck like those sold by Big Dog Toolworks. Grizzly, HF, LMS, MicroMark and others sell the SEIG.
I can't say anything really clearly recommends one over the other. If you are looking for one of the Real Bull lathes, I think the tooling included from Big Dog Toolworks comes out a better bargain over the Ebay pricing. Also, be certain the leadscrew matches what you are looking for. There are metric and SAE versions.