www.dipyourcar.com is where I bought my product online. I didn't do a ton of cross shopping, but their prices seemed reasonable. The two pieces of advice that my friend gave me (he even came over and helped out) that were key are:
1. Make sure the spray cans are WARM and well mixed. It was a sixty degree day and he still had us warming the cans with a blow dryer. The minute we tried to spray a can that had cooled down the product came out in blotches. WARM THOSE CANS!
2.To mask the tire from the edge of the rim use 3 x 5 index cards placed in around the edge. This worked like a champ. It was easy to set up (my 14 year old did it), was very effective and the cards came out easily and didn't stick to the rims.
I even sprayed my EZ-Pass (I always hated that white thing up on my windshield).