I have at least two sources for caapi leaves

1) Bouncing bear in US has them, http://www.bouncingbearbotanicals.com/ayahuasca-vine-p-286.html They are the "foliage" product of course. They also show the jaguar enjoying the leaves, I suppose not because they are rich in meat.

2) Spiritgarden ethnobotanicals in UK also sell them, http://www.spiritgarden.co.uk/cart/index.pl/catid_1/proid_83/_/_/Banisteriopsiscaapi/

There may have a fair source of THH. The vendor of pure THH claims to extract it from caapi (or syrian rue sometimes). Extracting from caapi is not that cost-effective if one is extracting the trunk, even if one is doing it in real bulk.

But leaves could be the key; it is from caapi as they claim and it can be found in massive abundance. Who buys the leaves anyway? I bet if this is their source they can find kilos of them for a very cheap price and extract it. That would make sense cost-effective wise. And caapi growing at one's property can produce a fair amount of leaves.