The components of Ayahuasca are easily found on the internet as they are not illegal in themselves (for example Mimosa Hostilis bark is used to dye clothing).
Then you can also easily buy Peganum Harmala seeds.
You can take these two orally or extract the harmaline from the seeds so you have less nausea.
You can drink as tea or other methods that you prefer.
You will always need a DMT source and a MAOI.
DMT source includes Mimosa Hostilis root bark as well other plants.
MAOI is necessary so you can have an actual trip, otherwise the only other method would be to smoke/vape it, but you would need to extract the DMT from the plant.
Smoke DMT = 15-20min trip but you need to extract and it takes some reading and preparation.
Ayahuasca = will take longer, usually 4-6 hours, but might have vomit and maybe nausea. Reportedly more healing, however. Easier to prepare. Perhaps there are ways to reduce nausea but most like not the vomiting.
Pharmahuasca = Same thing as above but you encapsulate the ingredients in pill form so it's easier to ingest with fewer side effects.
Alternatively I heard shrooms can also be very intense and can be potentiated. Lemon can also reduce the nausea of shrooms.
I wouldn't buy DMT on the internet. Lots of scams and usually overpriced.