Even in perfect condition, the price may be a little high but cant tell without looking at it. If it's been sitting long, it's common to get spiders and crud in the orifices of the appliances. If it's not working on electric either, it has other problems. Worse case is a new frig. If you are going to keep it in a park and live in it, you may be able to buy a home type frig for a lot less money. It's common for RV frig to be over $1,000.
Other factors enter into the price also such as how much time do you have to shop and how far can you travel over and over only to be disappointed by more lies from people selling junk. What may seem like a high price to me or someone else may work out well for you in your market. Number one is to be dog gone sure it has no water damage.
In order of value it would be roughly like this
Refig $1,000 plus
Ac unit $500 to $600 plus
Furnace $400.00 plus
Water heater $300.00 plus
Water pump $70.00
Holding tank $200 and up
OH! I almost forgot to ask......you are the handyman type aren't you? :)