All the plans I tried off the internet or ebay we not worth much. The best money I spent was for Steve Fredericks builders manual his inside out techniques will show you do not really need plans.
http://www.campingclassics.com/. His web site has lots of pictures from several of his builds that gave me ideas. I had some of my own scratch drawing and used his technique and built my teardrop.
Good luck with your build
Dan