Changes

If you are out of luck and forced to take a colectivo, haggle like crazy. The price is a total rip-off relative to the distance travelled, and if you haggle with a smile, most times they will relent :)

In order to enter the arqueological site you have to pay, and by paying you get a wristband that from time to time you need to show in certain places (like some special jungle paths, but this is usually on the most touristic days/places). There is a way to enter without paying and that is to take a left right before the entrance (a stone arch with the people asking you to pay) and go to the restaurant and hut complex, if you keep walking thru the restaurant and try to keep your walking paralel to the main entry road to the arqueological complex, soon you should be able to walk thru the bush or find a path to it without paying. This can be simplified if you come right after the entry offices close as they leave the gates open (somewhere around 18hs but that might change depending on the season), which shows how much they care about the entrance fee. A justification to do so is that you can stay in the arqueological site for weeks if not months and they would expect you to pay the entrance every couple days, which is absurd if you are staying inside and already paying for lodging/camping. Nobody will hassle you about your lack of wristband, specially if you explain that you are staying at some camping place and that you take it out when you shower and forgot to put it back in (be creative or most people will have the same excuse). Entering the actual arqueological site (where the ruins are) is a bit more tricky (Hint: walk thru the river against the current until you reach the site). Id say its decent to consider paying once for entrance to both the arqueological site + jungle and the ruins itself, but you might feel like the whole place deserves a month long stay and then you might feel like finding your way around it without going bankrupt. Another thing to do is to hang out by the main road and when you see people on their obvious way out ask them if they can give you their wristbands/tickets.