Airport Shuttle, prepay or pay when I arrive?

Arriving at midnight on June 19th. Was thinking of using www.airportshuttle.com to price. Do people usually just get a quote when they arrive or book online? @ adults 3 kids staying at westgate resort which doesn’t have shuttle service.
Thanks
Ed

With 4 or more people you’re likely better off hiring a direct card service than trying to do a van shuttle with other people. I’ve used Orlando Tranportation by Mike, about $130 round trip for a nice large SUV to and from the airport.