Contact a Forest River dealer to get a trade in value.
Additionally, blue book values are available from NADA Guides. This can also help you guage the value.
Websites such as RVTrader.com can be used to get an idea what similar RVs are selling for.
You will need the specific model number, options, location/zip code and to look under the manufacturer name [Flagstaff by Forest River].
Go to [www.nadaguides.com]
Select = [RVS]
Select = [Travel Trailers / 5th Wheels]
Select Manufacturer = [Flagstaff by Forest River]
Select Year =  < start here
Select Model = [8528RLSS]
Enter Zip Code = 
Options = [Select]
[Get Base Pricing]
Suggested list price = $24403
Low retail = $4560
Average retail = $5500