Cheap once you are there and expensive to reach if you let an agency package it — the boat in and the guided tours are the entire budget.
Go via Cariari and La Pavona
The public route is a bus from San José to Cariari, a second bus to the La Pavona dock and then a public boat down the canal to the village. It takes most of a day and costs a fraction of the door-to-door shuttle that most agencies sell.
The flight is the alternative
Sansa flies San José to Tortuguero, which compresses that entire day into about half an hour. It is the most expensive single line you can add to a trip here, so be clear about what you are buying.
Buy park entry through SINAC, not a hotel
Tortuguero National Park entry is handled through SINAC's own online reservation system or at the ranger station, and guided tours inside the park are compulsory. Booking directly avoids the mark-up hotels add for doing the same thing.
The Sea Turtle Conservancy visitor centre
The STC's small museum sits 200 m north of the Tortuguero school, open daily 08:00–12:00 and 13:00–17:00 for US$2.50 a head. It is the cheapest hour of real information here and the fee goes back into the research station.
What a day costs
In the village a basic room runs roughly ₡12,000–20,000, a soda plate ₡4,000–6,000, the public boat from La Pavona a few thousand colones each way, and the STC centre US$2.50. Guided tours — a canal boat or a turtle walk — are the real expense and typically run US$20–35 each.