When I was looking at class Cs, I was looking for something in the same range as you are looking (12-15K). The dealers that had Cs in this price range were smaller and didn't have their own financing. They simply went to your credit union for you. As the Cs in that price range were 15-25 years old, I then ran into the problem that the credit union wouldn't loan on anything over 10 years. If I wanted to finance, I'd have to get a personal loan or mess with a line of equity, etc.
In the end, I looked at the options and decided that putting all my cash into an older and less expensive C and using my "monthly payment" money into bringing it up to proper condition was a better way for me. I got really lucky when the American Clipper showed up at a local dealer - it was in far better shape and much better built than those "newer" RVs I had been looking at originally. I likely would have put out the same amount of money in repairs on a $12-15K rig.
The above may not be right for you, but just throwing out another option to finding financing.