Ran across this on this morning:
http://nmi.craigslist.org/rvs/4564647802.html

For Sale- 1992 Barth 28' Diesel Motorhome/RV - $27500 (West Branch, MI)

condition: excellent size / dimensions: 28'

Posting for a friend. Please take a look and tell your friends!! Only 80,000 miles on it. 28' long, 5 speed automatic transmission, Diesel 5.9 Cummins engine, Spartan chasis. Great condition, has an awning. Located in West Branch, ask for Mark
show contact info
$27,500 obo.

I am very doubtful that this would be a 5 speed unless it has been modified.

You can see the gear selector LEVER for the Alli four speed.
Coach appears to have significant lower body corrosion. I feel like I have seen this one before because the bungy on the armrest look familiar.

Located in West Branch, ask for Mark (989)329-7063. $27,500 obo.

FWIW, NADA Average Retail, $11950. Here is one case where I don't think NADA is much of a measure. Recent activity would indicate a higher value. But, as many know, you have to see it and drive it. And as others also have said, the market value is whatever a buyer and seller agree on at a given time. But, with the internet, many people have access to a lot of information(some good, some bad) and shoppers are hopefully more discriminating than ever(or at least think they are).
Jim