Alicante's Airport is located just 43 km away from Benidorm in one of the most enterprising and dynamic areas of Spain. It offers you the chance of enjoying modern and equipped installations and services. Most of the low cost companies fly to Alicante. There you can get a coach that will take you to Benidorm in around 40 minutes.
Visit this site to find which company is the best for you:
You can book a shared Shuttle bus from the airport to Benidorm and back for a very reasonable price:
Valencia's airport is a good option too. It's around a 90 minutes drive. Here is a link for low cost flights to Valencia:
If you need more info about Benidorm, visit the following link: