I would order online from Bulk Reef Supply. Check out this page:
http://www.bulkreefsupply.com/store/...zation-systems
Quality units for a good price. I ordered the 6 stage deluxe system last month. It came delivered in 2 weeks and was $50.00 to ship. The good thing about these units is the cheap filters. Order some extra filters at the same time. It can be pricy for DI resin in certain places and from BRS I think its about $8.00 for a cartridge refill. I would get one with a TDS meter so ya know when your DI is toast. The 5 stage plus system is a good deal. If you get in a group buy it is only $180.00. Best of luck!