Honda calls it the Seat Cowl or Cowl Set. It's part number 77216-MAL-A01Zx with the x being a different letter depending on the color code. New they're between 70.00 and 100.00.
I get a lot of factory parts from mrcycles.com. They've got the parts schematics for all the Japanese bikes online, which is very helpful, and usually the parts are at a good discount. The cowl is found on the "Seat" schematic for the F3.
You can also find used bodywork on eBay. Just keep an eye on the price; often used parts are almost as much as the discounted factory parts.