Somewhere online was a document that showed original retail on vintage coaches and for the life of me I can't find it.
You want to get appriased value if it's in any kind of shape. Your original price was around $2700 new. Unless you got a smoking deal or it's rough I bet you already paid more for it.
I'm in the same boat and currently Our Coach is insured for $2738, original purchace price. Once I get it restored I'll have it appraised and insured bassed on that.
Right now the smaller coaches, like yours, are fetching the big bucks. Restored Bambies are well over $10k now.
would be a good place to start on what it's worth. VintageAirstream.com as a whole is a great recsource. Hit the link page and they have some more insurance information.
Also are you just lookin in the Forums or using the Search feature at the top right of the page? Should be a few insurance related posts.