Wheel Spacers

I traded a set of stock wheels and two sets stock tires for a set of 28" mudzillas on a set of itp c series nearly new. Only hitch was they came off of a Yamaha Grizzly and the backspacing is different. It rubs the muffler. I borrowed a set of 2 inch spacers and it works fine. I was wondering where the cheapest place to order the "ring type" spacers was. Any help will be appreciated.