The costs include a $30 Coleman cooler from Wally World (Walmart), two 10" pneumatic tires from Northern Tool at $10/each, $3 worth of 1" schedule 40 PVC, $3 for some bathroom caulking, $2 for two cotter pins, and $10 for a 3' piece of 5/8" zinc platted steel rod from Lowes. I like the cooler for camping because it holds ice a long time, so I figured an up-fit would allow for me to use the big tires on the beach and the factory tires for my everyday activities.
I thought about buying the big grey beach wheels, but they were $50 to $60 each.
6/24/2013 - UPDATE - My version of this cooler doesn't fit through a lot of doors really easy, so if you fill it up at the fridge or indoors you may have to pick it up to get it out of the house. I'm probably going to do a modification on a different cooler that will fit through doors for my family style vacations (see the version in the comments section - thanks to the commenter for sharing their version). The one disadvantage I see to the longer cooler is that you will have to bear more of the weight of the cooler while dragging it. If you are going to drag a cooler for a long distance, the version of the cooler that I show in these pictures may be somewhat easier to move. I'll hopefully have the chance to verify this when I test out a modification to another cooler.