Pat, NADA Guides (found online) tracks current values of RV's in your zip code and you can look them up for free.
Currently, they list only Dealer (aka Retail) sale amounts, Private Party sales are usually less than Dealer/Retail because a dealer needs to pay for labor and facilities to make sure everything is working fine while Private Party sales are usually As Is.
Also, when using the site, be sure not to double count accessories like the air conditioner, furnace, microwave, awning, etc. The prices already include everything that was standard, not options. Our Sunlines had a lot that was standard and therefore already counted or built into the price. You'll have to see if you have anything that was optional when it was purchased. Chances are you have only a few options, like the outdoor grill, for example.
I hope that helps.
P.S. You can always pick a higher price to start but if no one is willing to pay it, you'll gradually have to lower it until you find the true value (which is what people are willing to pay).
P.P.S. I sold our T1950 many years ago; if you advertise on craigslist, I can email you the really nice ad I made which covers all the features and advantages of the Sunline T1950 ...just let me know.