Lowes carry a couple of real nice affordable smaller ones.
I bought one on the recommendation of my Mobile Repair guy to use during the summer to assist the AC. What a DIFFERENCE it made on how much cooler it was in the MH.
Be sure to get one with a long enough hose so you can have it drain into your shower. Otherwise you have to keep emptying the water cup from it or it shuts off when it reaches the top of the cup.
I found it amazing just how much water it drew out of the inside of the RV!