Amazon seems to have the best price on NOLS Soft Paths, 2003 Ed. This and other excellent LNT guides are easily found in libraries, but frequent outdoorspeople will benefit from having a copy of their own.
Here, under Misc Resources, you can buy the ethics booklets for geographic areas, for Boy Scout dissemination, and by activity. Most range in price from free (online) to $2.95 (print).
A Master Educator course is really only worthwhile if you need/want it on your resume, or if you just want the extra field experience. Otherwise the LNT 2-Day Trainer Course is affordable and fun.
Also, a partial bibliography to scholarly research can be found here.
To TP or not to TP is just not the question, and I don't think its what this discussion is really about either. Generally ‘resistant’ attitudes give the impression that various actual practices are taking place, according to whim, circumstance or lack of preparatory thinking. As the article puts it, ‘We don't have to deal with it in the bathroom, and that transfers to people not “dealing” in the backcountry too.’