injection gives greater levels in the blood than transdermal which is generaly greater than oral, depending on the drug, most methylated compounds give lots to the bloodstream.
theres lots of debate as to how much of a transdermal gets into the system but I've seen figures like 20% for 1-test, although Im sure someoneknows better!
powders are cheap and versatile, you can steralise and dilute them and inject, cap them, suspend them in alchol and take oraly or put them in a transdermal mix and use em that way.