Hi Thomas,
It's really hard to put a value on a used Sunline, especially without seeing pictures. I feel like we are also on a downward trend from Covid pricing, which created a lot of demand in the RV world.
Depending on the work done, current condition, age of tires, moisture meter readings, and many more factors, the value can vary by a couple thousand. There are exceptions, either really well preserved original trailers or professionally restored trailers can command much higher numbers.