Has anyone tracked what's happening with Vanagon values lately?

This from the NADA BUYERS GUIDE. I pulled this up yesterday,

1991 Volkswagen Vanagon Carat

May 1, 2015
Original MSRP  Low Retail  Average Retail    High Retail
$18735                 $4800            $8300                $15000

May 1, 2017
$18735                 $6050             $10550              $18300

Over a two year span this is terrific if you are selling, not so good if
you are buying. Of course all the real value is in what you sell or buy it
for!

John