This paper by a PhD, may be of help.
I especially like the idea of getting rennet in small quantities, not liters and liters, or kilos of dried, from the "big guys" (Junket brand, 8 tabs/1.50 USD from the maker, about 2.50 from online sources)
According to the Doctor, one tab will clabber 5 gallons of milk. Perfect for the beginner, who wants to control costs.
http://biology.clc.uc.edu/fankhauser/ch ... ennet.html