RV 2000 SUNLINE M-1950 prices, specs and options at NADAguides.com
That's the most recent NADA value. That still seems a little low to me, it is somewhat new and small/lightweight, so I don't think it should be worth about the same that a '80's 1550 in mint condition should. I say something between $4500 and $5500 is fair in the current market. As I said, it's small/lightweight, and isn't that old, so it would be pretty popular for people with the smaller tow vehicles and limited storage space.
2007 T-286SR Cherry/Granola, #6236, original owner, current mileage: 9467.8 (as of 5/26/19)
1997 T-2653 Blue Denim, #5471
1979 12 1/2' MC, Beige & Avocado, #4639
Past Sunlines: '97 T-2653 #5089, '94 T-2251, '86 T-1550, '94 T-2363, '98 T-270SR