I hope I'm not to late, but I purchased my RO/DI 4 stage water filtering system from Buckeye field supply. Their prices are great and if you have any questions the guy will call you back or contact you via email. The service is exceptional. I hope this helps. If you already purchased one I hope this is a good reference for others in the future.
Here's their website:
http://www.buckeyefieldsupply.com/sh...ry=167&Sub=166