Just got back from a week in Punta De Mita. Very relaxing stay at a beachfront condo on Emiliano Zapata beach. Here is some info I thought might be helpful. A taxi from the airport to our condo was $1200 pesos. For the way back to the airport, I made arrangements the night before with the guys at the taxi stand on El Anclote for a morning pick up. The price was the same on the way back -- $1200 pesos. They arrived on time and got us to the airport with no issues. I would do it the same way again.
For our trip to the Marietas Islands, we took the advice we saw here and booked a trip with Rudi at the coop. The price was approx. $2200 pesos for two people on our own boat ($2000 for the boat, and $160 for 2 government required wrist bands). This was a 2 hour trip that included a tour around the islands by boat, snorkeling and swimming at a little beach. We saw the beautiful islands, plenty of blue footed boobies and other birds, and plenty of fish while snorkeling. We went in the early morning at about 8:30 a.m. And beat the rush. We had a great time and would recommend doing this trip. This trip did not include the hidden beach - which is significantly more expensive and from what I gathered required going with a larger group later in the day.
I think I could have probably haggled for lower prices for the trip to the Marietas and the taxi ride back, but with the prices being so reasonable, and the exchange rate so favorable, I had no issues paying asking price.
Let me know if you have any questions.