Theres a ton of info on the forums about this ... If a search isn't working, use google. Its easier to find info on the nexus through that most of the time
People basically use either syrian rue (paganum harmala), ayahuasca vine (banisteriopsis caapi), or harmalas extracted from one of these two vines. You can also separate the harmine or harmaline if you want but i don't see much of a point..or you could buy them like that from some sites (its a total rip off).
I don't notice much difference between caapi and rue to be honest. I love them both immensely and take them very often. They're deep medicines by themselves and are very psychedelic at high doses if you lay down in the dark, but in a way that is unlike almost anything else i've encountered. its a very powerful, interesting, and unique experience. People get all caught up with the mao inhibiting part and don't realize that if anything, the harmala plant is in a lot of ways the main ingredient. Caapi has been referred to as the 'force' whereas chacruna (dmt containing admixture) is the 'light'..caapi is like the cave, and chacruna the torch that lights up the cave
Most of the time when i do aya i prefer taking an amount that is psychedelic on its own, and then adding the desired amount of mimosa/dmt (you wont need too much). Its a very very different experience than if you'd only enough harmalas to activate dmt in the gut and a big dose of dmt
<Ringworm>hehehe, it's all fun and games till someone loses an "I"