I bought a RO system from this site:

http://purewaterexpress.com/

Sato's customer service is top notch- when I had some leakage after changing filters this year, he helped me track down what the problem was by email. On New Year's Day.

I got the Slimline II model HTF-101 from Hydrotech, but the new quick-change model looks really slick.

One big difference between this and the ones you get at the big box stores is how the membrane works. The big box ones have membranes that need chlorine, but they only last a year. The ones from this site have chlorine sensitive ones, so it needs a carbon filter in front of the RO filter. But the membrane lasts 3-5 years.