I was thinking about your problem, when it hit me... You should build a swamp cooler, on a small scale of course, I drew a shitty picture of what it is, but I'll explain it anyhow...

A swamp cooler works by passing air over a radiator like surface that is constantly having cool/cold water pumped through it.

***DISCLAIMER***

!!! I have not built this device !!!, but it operates on the same principles as some types of large commercial/industrial air cooling units.

Now since you have a fan already running, all you have to do is put the device in front of your fan, for the size of operation you have, a small radiator is needed, I think that an old heater core would be perfect, if you cannot come across one of these that does not leak for free or VERY cheap, you could use flexible copper line and bend it like in my second pic and use it in place of the heater core, the pump, a small one, as cheap as you can find, as it does not need to pump a great deal of water, then fill the reservoir with cool tap water, and for the extra cooling effect put some ice in the water, or get one of those blue-ice things and toss it in there, as for the reservoir, I would recommend using a cooler, but a rubbermaid container will do, the way I see it you could probably put this together for about $50 or less.


BTW. You can use rubber/PVC tubing to attach the pump to the heater core/copper tubing rig.


If you build one of these I'm sure it will work for your purposes, and you could use it on a timer for a fairly steady climate control, but if you want to do this uber cheap, just freeze a couple of 1 liter soda bottles full of water and position them like 6" in front of your fan.

Hope this helps...

L0rdsOth