"He offered me human blood - said it would get me higher than I'd ever been in my life" -Fear and loathing in Las Vegas
...so this raises the question of where the blood comes from, whether it's human, and in the case of Ra, how human it needs to be for her to metabolise it or whatever she does with it.
(And also what other dubious substances Tish is happy to push.)
Oh, blood's easy to get if you don't care what kind. Butchers are pretty happy to give out cow blood, for instance.
Human blood...? Bit more difficult if you're trying not to assault people :P
Are there safe ways to draw blood in this world? Tish's offer is nice and all but I gotta wonder what the normal means of acquisition is...
Mortuaries, maybe? Not sure how good that blood would be...