This one looks like it might be a good start. Hard to tell from the pics, but it doesn't look too bad. Says it was covered with a tarp for a few years, but Yakima is a dry place. http://seattle.craigslist.org/see/cto/3727676045.html
The entire columbia basin is great for preserving cars. Yakima is on the western edge but still should provide pretty good protection. mike
Looks like a nice solid little wagon, and certainly seems priced right for the condition. It may even be priced a bit low for the condition, once it is gone over carefully.