I think you should think this very well, though. Im sure you have also heard about ayahuasca tourism becoming mainstream, and the negative effects it has on local culture too. There are a lot of unscrupulous "shamans" out there, and in places like iquitos I hear you dont even leave the airport and you already receive ayahuasca offers.

The other option you have is going to an already known retreat. These retreats tend to be very expensive and are much more adapted to western cultures. If you check out reviews, im sure you can find some very well organized retreats with curanderos or similar who lead ceremonies very well. But I dont know how 'commercial' it will be, if you know what I mean. I would suggest if you take the trouble to go all the way to south america, maybe do spend a bit of time in a known retreat to have some good ritual guaranteed, but dont settle only for this, also travel around on your own (carefully!), and maybe find more genuine shamans off the beaten path. I would suggest learning a bit of spanish at least (or portuguese if you go to Brasil).

I dont know about much about peru (except of hearing that iquitos is generally a starting place to venture deeper), maybe others can help. In brazil the state of Acre (north-west on the tip near border with peru and bolivia) is where there is a big concentration of indigenous tribes that use ayahuasca, mostly the Huni Kuin. Some villages you might be able to go in, some you'll have to pay a certain fee for being there, some might not want a foreigner, it depends. Ive participated in several rituals with the huni kuin and it was very special, to say the least. Some areas they are getting a lot of influence from Santo Daime, though, which I am critical of for some reasons, but there's still plenty of original cultures and isolated tribes.

Do note that if you want to make a real amazon trip, a couple of weeks are not enough, sometimes it takes many days to reach a certain place. Usually one goes by small (scary) airplanes to closer destinations, and then boat travelling. Please make all the research regarding how to prepare for such experience. It may happen that people try to take advantage of foreigners, charging more, etc.. Some people are very easy prey, but if you're reasonably street-smart (or have some good sense) and specially if you also learn the language, you can get around well. Also, I think when you're a good hearted person, its much easier to get along well and have people respect you as a person.

Last thing I want to comment on is how you establish that contact. Often outsiders relate in very uni-directional way. People come, exploit the 'native with his exotic behaviors', pay some amount and leave, maybe feeling good about themselves. But unless there is some return, more than just money, this ends up leading into a very dry relationship of 'paying for consuming a service' and it kinda perverts the whole spirit. If you go to some culture, I suggest research first, see if there's anything you can contribute, maybe stay for longer if your life permits and work on a small project there. Or in the very least, when you're there, show respect for their culture, ask if you can help in the daily tasks, learn, teach whatever you can of useful, etc

Anyways these are just some ideas, whatever way you take, I hope it turns out great.

See you around

I think its important to also question why you are doing it.. Do you just want something exotic? Or do you want the intervention of a particular kind of shamanic ritual in your life? Im sure you are well aware that under the name 'shamanism' there is a host of very different practices.

Btw, as for KwisatzHaderach's comment regarding going to south america.. I dont think you can generalize that much. For sure there are some negative impacts regarding ayahuasca/shamanic tourism and some locals may look down on it, but it also represents an important source of income (fair in some cases, unscrupulously unfair in others). Then there are many locals which dont even question whether its good or bad, it just is. And yet others farther away who nearly never see tourists and might be very happy when someone from outside arrives. Theres many cases.

Also there is the question of cultural exchange, which can be very negative in many cases but in others it may be positive. If you just take an airplane to Iquitos, go with the first person that offers you ayahuasca when you step out of the airport, take whatever they offer, pay and leave again to tell the story to your friends, then I would say thats a problem. It would be completely different if you do your research first, know some basics about the cultures, if you go to either a trustable shaman you've been recommended or that you go away from the beaten path, into the jungle and carefully try to find 'the real deal'. Also specially if you try to think of ways that you can help the people you interact with (not necessarily monetarily or materially, maybe there's something you can teach them, maybe you can help them think critically regarding the 'gifts' that westerners bring, or maybe you wanna stay for longer and work on some project with them that they need, whatever)

So yeah, do it if you want, but do it consciously and the best way possible. If all 'shamanic tourists' were conscious and respectful, you can be sure it would be sooo much better, so if you do your part im sure it will be fine