Been here, done that. I've gone the water bottle route and it works, but it sucks having to put them in every 2-4 hours.
I even made a water chiller...I mean its a pretty basic idea....run water in a circle in something that's cold and then pump it out....so I got a deep freezer ($50 craigslist), 100' of some hose, and a water pump. Just coil up that hose in the freezer, cut some holes in the freezer to string the hose through, and put the water pump on a cycle timer or just straight on. It took quite a bit of temperature monitoring of the freezer and water reservoir. But I'm actually typing on top of the freezer right now with my laptop...works as a good table too!
I've also bought some 1/10 aqua chillers (325$ new). They're the best if you can afford it. I need a couple more...but for now, this freezer is going to have to do. I can put two hoses (for 2 res's) in this freezer and it works great.
NOTE: you gotta clean that hose out though...stuff builds up in there and can't be clean. I run 3% h202 through it for a while at least once a month.