got mine at Sams Club....its a 5 stage, cost me $150
I went and bought (3) 5 gallon drinking water jugs from my grocery store ( I had to ask, but they carried RO water in the big jugs)
I dumped the water in my tank, and now I just use a clear piece of airline tubing to run the water from the RO faucet and into the containers. Takes about 2 full days to get 15 gallons of water, then I just store them in the garage....they are perfect cuz I have a 55g so one of them is roughly a 10% water change....oh yeah, I got a 4th one, and its for the water siphoning out out my tank (vacuum)