Go on craigs list and get a roof top unit and put it in yourself. It goes where the vent is. If the manufacturer offers it as an option, then the support is already there. Bought mine on craigs for $150 3 years ago and it still works great. Even put in the heat strip for thoes cold nights early in the year. Runs off a 20 amp service. You will need some putty to place under the roof flange and some help getting it up there. My son-in-law and I put mine on. Just put a piece of plywood on the roof to support my fat A$$ and it was a piece of cake.
I can assure you, it's not worth $1,100.00 that they want.