Walk-in Humidor A/C

Hey everyone, I'm trying to build a walk-in humidor about 10'X12' inside my business. My concern is how should I keep it cool? I read another post about as long as the humidor does not join to an exterior wall that its ok to leave out the a/c vent. Maybe if the room was not insulated at all this would work? Doesnt seem like this would work in the scorching summers. Maybe just add a window unit for a couple hundred. Whats the overall best Method? Thanks for any help. Oh and the humidifier I ordered is the Trion 707 by fedders. The local store here seems to have a floor unit. I think its considered a whole house humidifier like this http://www.allergybuyersclubshopping...iers.html?dfnt