I used a driver Ana Luna who was excellent and a very nice person as well. She used to live in Miami and spoke perfect English. She gave us recommendations for shopping (local bargains) and restaurants. She immediately responded to my email request and was waiting for us with a sign at the airport. Everything was included for $20 US.
www.ana-luna.com
Just getting a taxi at the airport is probably cheaper but Ana was so wonderful and knowing that she would be there when we arrived was worth the extra couple of dollars.