Need help finding a cooler unit for small 6g Fish Tank

I know this isn't exactly how to cool a computer, but I know you guys deal with phase change and TEC on a regular basis. My gf has a saltwater tank that needs to keep below about 84F. She has been looking at some cheap units, but I noticed they were TEC and from what I remember if the ambient is warm, then the TEC will not be able to cool much below the ambient, correct?

So we would have to go with phase change I believe as the room is going to heat up to 97F while we're on vacation. Is there any cheap (under $150) way to create or purchase a unit that can keep the temperature below 84?

I'd check out what they do in an aquarium shop.

If you arent running that hot, you can try running a aeration stone and having a fan blow across the surface of the water. The evaporation should keep the temps down, but Id also get a small room A/C and have it keep the temps reasonable.
For the commercial route, this would be your best bet, but im sure some shopping will get you a lower price.
http://www.drsfostersmith.com/product/prod_display.cfm?c=3578+4900+15129&pcatid=15129