If you want to go "whole-hog" and get a proper knee-length linen shirt, I recommend one of these "hunting shirts" which come in various weights of linen, and colors (natural, walnut-dyed, etc.):
http://www.trailhd.com/shirts.html

For inexpensive poor man's "shoes" you can get a moccasin kit and sew up some simple highlander's "cuarans":
http://smoke-fire.com/moccasins-1.asp