(1) count the dings, dents, creases, major scratchs, hail dents on front and rear end caps, etc. Each curved panel is a $1700 replacement if required. (2) how much oxidation? $4000 to recoat(3) stored outside in the sun? (4) original owner? If there are a number of imperfections, can you live with them? You will know a good unit that has been stored inside.
(5) look at top of wheels vs bottom of wheel well, there should be 3-4" clearance or rubber bushings are compressing. (6) do you need new tires, are the tires wearing even, no bent axle. (7) if stored outside, check awnings for mildew. (9) does it have panorama windows in front with privacy glass, (10) how much rust on frame in front and rear, (11) two gas bottles aluminium, (12) check front wraparound windows for leaks, (13) good cover for gas bottles, (14) elec jack works? (15) spare tire under front, (16) look under front tongue area for wiring harness, has there been any "hot wiring" around problems. (17) does it have stone guards in front (18) do fold out alum steps work, do they have a brace to support weight.
This is just a start on the exterior. A/C unit on top, tv antennae on top, solar would be a plus.
I will do an interior if someone else does not. I think $14000 is at the top of the market price and needs to be an exceptionally good unit. How much have they spent on the trailer last five years?
I think Airstream was at the top of their game in the mid to late 1980's. My unit has been a very good trailer with much use.