Cody, the last two water heaters I bought were from ebay and cost about $380 each. There were propane/ac type heaters.
I would expect the dealer to be several hundred more just for the heater plus your install at probably $100/hr. Hard to say how many hours to do the job but I would bet a minimum of about 3.
Sorry I'm not much help.
Air forums # 1674
1974 20' Argosy Motor Home
1974 31' Excella trailer (parting out, as of 4/1/2015 I have wheels, brake drums, windows & holding tanks left to sell)