I have owned two of the Epilog lasers in 35w and 50w. They are really easy and reliable little machines with great support. A friend got one of these off-brand machines and had nothing but struggles. First, the laser was bad from the beginning in addition to various motion control issues. Once he got past that, the software was at least as fiddly and crappy. After that, the actual marking performance was on par with what was paid - poor.
While the Epilog's are not industrial machines, they are VASTLY better machines with a price tag that is appropriately higher. After seeing what I saw, I would not waste my time or money on these eBay specials. They seem cheap until you fiddle with them constantly and never get more than a marginal result. There is a chance you may be more lucky, but would not count on it.