Hello tslanier -- From your profile 'threads started' I see you have been going about your search in an organized fashion. The 1990-1999 Airstreams have their followers in the Forums and I'd hope you get some replies. The trailer you are looking at is too new to have been included on VintageAirstream's "Price vs. Condition" page.
Can you give us a 'flavor' of what you mean by excellent? Has it been stored inside our out? Have the tires ever been replaced? How good is the condition of the skin and clearcoat? Does the A/C work? A photograph or two could thaw the heart of a 10 year old Excella owner ...
When I ask if the A/C works, please don't have the current owner start it for you in their driveway unless they have a 30 amp outlet (ie, didn't have to use an adaptor on the power cord) -- that could be very bad on the compressor.
Good luck in your search!