There are a number of hotels on the island ranging in price from $80 - $130 / night. Bruna and I recommend a hotel called Porto Pacuiba: http://portopacuiba.com.br/ It's both low-key and funky but also extremely comfortable. We'll be staying at an Airbnb within walking distance.
The most straightforward way to get to Ilhabela is to fly into the São Paulo called Guarulhos (GRU). You'll then have to travel by car to the Ilhabela ferry. It's a short, beautiful ferry ride then you're on the island! We'll be updating you all with some other options for carpooling from the airport in the near future.