[FungalRaincloud]

I don't think there's any reason one could not lace heroin with AIDS, it just would not reflect well on a dealer. That said, it would likely require intent (or really bizarre circumstances). With blood, it could much more easily happen, you're right.

Many young people already do give up their blood for a pretty cheap price, so I don't think there's any reason for this to become a black market thing.