Not sure you need anything else, unless it's something required by your locality. Selling a mobile home is closer to the process to sell a car than to sell real estate (assuming there's no land attached).
However, I don't understand the appraisal. If you'd wanted one, it should have been done before you marketed the property; if you have a buyer, you've probably already advertised/quoted a price. What if it appraises for more; are you going to tell him: "Sorry, but now I want more money"?
Also, mobile homes don't appreciate, certainly not like real estate. In fact, like cars, they depreciate. So, generally, a mobile home seller is pleased to sell the home for what he/she paid. I know plenty of mobile home owners who would be delighted to sell for what they paid for. You might use this as a gauge in your pricing. And, of course, if you're in a mobile home park, look at what similar homes are selling for.