Disney world to beach and back!

My son and I are finalizing our plans for our first trip to disney at the end of this month! He has mentioned wanting to take a day to go to the beach. We are flying down and not renting a car. What is the cheapest and quickest way to go to the beach? Are there any shuttles or buses that do this type of service?

Renting a car is going to be the cheapest and quickest way.

Definitely a one day rental would be your best bet and with any luck you would probably be able to get something for $40-$60 range
The closest beach is Cocoa Beach and its a little over 70 miles away, Daytona beach is just over 80 miles (our favorite Florida beach) and Clearwater/St Petes is almost 100 miles away.
Taxis and town cars will make the trip but you are looking at $300 and up for a round trip (plus most are looking for a 15-20% gratuity on top).
Uber is available in Orlando, but not sure if they will do this kind of trip or how they would handle the return leg of the trip.

If you really want to have a beach day, price out a one day car rental from one of the agencies that are on property. Some good info about rental locations on property found in this thread: http://www.disboards.com/threads/car-rental-locations-for-wdw.2927109/
Alamo from either the Car Care Center or The Swan would probably be our choice and they will shuttle you to the facility if you call ahead and book.

Uber might actually be available for this. I was in Boston a few weeks ago, andanUberdriver picked up a group of men and took them to Vermont.