I've always assumed the "lower" prices on used '34's is due to a combo of economics and modern trends. Yup, your gonna need a HD truck to haul it, ( 3/4 - 1 ton ) and that truck is gonna cost more to maintain, burn more gas and cost more to purchase. ( More than say.... an F150 ) Some will say the length is prohibitive at some parks & monuments, but arguably very few ( think North Eastern USA) Hauling one is a cinch. They "track" behind your vehicle well and if you know how to back a trailer, backing a '34 triple axel is a dream. #backinginslowmotion. The biggest drawback is making tight turns or U-turns requires quite a bit of space and is usually very hard on your tires.
As much as we love the "newer" Airstreams, I believe the build quality of the older Airstreams is better as well. ( Just personal opinion)
2013 Ram Power Wagon 2500 4X4 5.7 Hemi
2001 Airstream '34 Limited
Fulltime in 2013 and LOVING it !!