Walmart offers the Intex Krystal Clear Saltwater System, model no. 28669EG, for $129.88 with free shipping. (Amazon and VM Innovations both have it for the same price.) That's $70 off. It features a 24-hour auto-clock cycle, purports to clean a maximum pool size of 15,000 gallons, and requires a filter pump with a flow rate between 700gph to 3,000gph.
Update: The price at Walmart has dropped to $99.88.