I sold all my shrimp just in time! :-)
This was my biggest pet peeve about keeping shrimp. Last year I purchased one of those big portable AC units and had it blowing right on the tank. It worked great but evaporation was insane. Temp was at exactly 72 degrees. Between the portable unit and central air, my electrical bill quadrupled during the summer months....still was much cheaper than having my shrimp die. If I had to do it all over again, I'd get a chiller even though the initial set up cost is pretty high. I am more into the aesthetics instead of having giant AC units or clip on fans all over the place.
For those of you who are fairly new to the hobby I would suggest you get something quickly and be proactive. In the next few weeks there will be a flood of threads on here about people's shrimp dying or various bacterial infections. Much of these are attributed to high temperatures as shrimp get stressed.
I loved my shrimp...I was very good at breeding and keeping them. But switching over to planted tanks without shrimp worked out better for my lifestyle. No fans and no AC units is a big stress relief.
Good luck all.