I have put below my best guess on the value of your coach. The only thing that would change it (other than major damage) would be if you had the fiberglass exterior option. To the best of my knowledge, this was the most expensive option available and it is (IMO) the only significant one that would affect the value. If you have this, add $1300-$1600 to those numbers, based on the condition of the fiberglass.
If you are really wanting to get rid of the coach fast, I would ask between $19,000 and $22,000.
If you would like to get rid of it, but you aren't in a real big hurry, I'd ask between $26,000 and $28,000.
P.S. These ranges are based on the current NADA blue book values for your coach. I have given you the ranges to see what I would ask depending on how quick I needed to get rid of it or how the condition is.
NADA Value Link for '07 T-276SR
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