Average or Common Markdown % off MSRP on Used Motorhomes

I check the RV for sale sites for like models and see what they are selling for. Used RV's are will only be worth what the buying public will pay for them. Some Mfgr's units are worth more than others. You can't tell what a dealer paid for the RV. I bought my present Dutch Star from a private party when it was 2 yrs old and would buy the same way again.