When we were at AK in WDW in April 2000 we bought a canteen that had a fan on the front, a mister/spray nozzle on top, and another opening on top (for filling and drinking out of). Don't remember the cost, just remember feeling that it was reasonable considering how hot we were that day.
We plan on packing it and taking it back with us this April when we return for 2 weeks. Even tho the investment was worth it the first time, since I already have one I'd feel buying a 2nd one would be a big waste of $$$.