I would suggest you check out Aquarite prices on Ebay. I picked up a brand new unit from a pool dealer last year for $400.00. It seems to be working great on my AG 26000 gallon pool that was installed this spring. It came with a 5 year prorated warranty.

It did require about 600 lbs of salt, but that was the only other expense. I have a two speed pump and am running the unit on low speed for 12 hours a day. Seems to be holding chlorine at the right levels. I just didn't want to be bothered with constant bleach purchases and additives. This is far more convenient.