The quality of the actual unit is heavier and more sturdy. It's also a full size unit so it is at least twice as big as the ebay model. But you can buy standard size replacement filters with the more expensive one while the ebay one needs to have them come from the same company. They have a website called P U R E W A T E R C L U B
you can check out all their units if you like.
Both will give you the cleanest water, no difference as far as that. End results are the same. I only think your filters would be changed 6-9 months since your not making very much, it probably would be longer. I got almost 8 months out of my set of filters recently and I make hundreds of gallons a month.
Oh and the cheap one will make water faster by about half the time. You get like 5 g an hour and 2.something with the BRS one. It has to do with the actual RO