Krylon Fusion, a ratcheting wrench for those hard-to-reach bolts, and an afternoon of your time. I did some yard work while I was waiting to add a second coat. My Krylon-sprayed fenders went through two Midwest winters, one of which was filled with record-breaking temperatures and terrible conditions. They still looked great when spring rolled around.
Most importantly: whatever product you end up using,
follow the instructions on the can, including the prep! I guarantee you will waste your time if you pop off the fenders and haphazardly spray them down without paying attention to the instructions.