I have a dozen miners too.... S1's, S3's, an S4 and 4 S5's... I am probably hotter than you due to my older process miners still running.
My secret weapon is a 3,000 CFM blower in a small room. Takes me from 35C down to 30C in less than an hour with 35C outside.
If you have proper ventilation, you don't need AC... that's double true if you live in a Northern country.
All I have is a 3,000 CFM Blower which is sold by NorthernTool and a $50 24" walmart fan to feed the mine with airflow from another room.
Again, it's loud but if you're a miner, loud noises are part of the trade.
http://screencast.com/t/mjfFXEQIp - Blower
It is loud as hell but I only needed to run it a total of 28 hours since the summer started.
Without it, I would have had to shut everything down anything S3 and under...
I live in Canada though, where the hottest summer temps so far was 35C outside.
Even at the temp it was a battle keeping it cool in the mine, the blower was the hero.
For about $150, was a great investment for airflow.