If you are on a tight budget, you can take a combi (minibús) to downtown Zihuatanejo and then transfer to another bus to Ixtapa. Just walk across the parking lot to the exit and the combis to Zihua are on the right. When you get to downtown Zihuatanejo, just ask for the bus to Ixtapa.

Note: As you are walking across the airport parking lot, the cost of taking a taxi will fall as the taxistas compete for your business.

I must not have the right look. I have done that walk across the parking lot at least a dozen times and never been offered a fare.

Note: As you are walking across the airport parking lot, the cost of taking a taxi will fall as the taxistas compete for your business.