I would look at homes on craigslist in your area. Find similar ones in similar condition, get an average value and subract x% (remember, you are a retailer/reseller who is selling a product to an end user and you deserve to make money on the deal). Also subtract approx $3,500 (more or less) because you have to move the home to your park. Be cautious.. make sure the average value you come up with is a value that will be an acceptable price for that home in your park. You may consider running a test ad to see if you get inquiries on the home at the selling price.