The best model-size pulsejets available today are made by Earl Bailey in Houston, Texas. The engine is a Dynajet clone, but manufactured to a much higher standard and reasonably priced. He did have trouble supplying them for several years, but I believe that is all behind him now. Sorry, no web presence, but here is his contact info:

Bailey Machine Service
633 W Parker Road
Houston, TX 77091
713-694-7017

BTW, here's a link to an interesting pulsejet model

http://www.btemodels.com/doublewhammy.html