I've been trying to find ways to save water as well, not exactly do to cost (water is cheap) but also for conservational reasons and my future development of an auto brew system.
Why couldn't you rescue an old radiator of some sort (car, junkyard...) Hook your copper wort chiller onto it with an inline pump. Maybe add a fan. This would give you a closed cooling system.
If you already had the wort chiller, I bet the most expensive component would be the pump. Sparkfun as a 350gph pump that I bet would work great. ($20 I think)
Again, perfect for an automatic brewing system.