You know the prices in your area better than most of us would. Around here, $10K would be a good price and a quick sale if it's in good, clean, solid shape.
I have a '98 Coachmen Santara 315QB on the same E-SuperDuty chassis, and I've generally been happy with it so far. Do check carefully for water damage (which is fortunately less likely when it's been stored indoors) and inspect all the caulking and seams, particularly around the roof and cabover structure, and touch up or redo any that are questionable. Also check the date codes on the tires; if they're over about seven years old, they should be replaced or at the least inspected by a qualified person (which generally involves unmounting them and checking the insides as well as the outsides). It cost me about $1000 to replace six tires at a local tire shop, keeping one of the old ones for the spare.
While obviously built to a price point, with cabinetry that isn't fancy and occasional minor fit and finish imperfections and so forth, I've found the design of mine to be pretty well thought through--with reasonable access provided to systems and valves and stuff--and the electrical and plumbing and mechanical systems constructed and installed in a satisfactorily workmanlike manner.
(For what it's worth, the E-SuperDuty was renamed to be the E-450 in later years, and often parts store databases and so forth only have the latter designation listed.)
