Zeek
CK worldwide make a few items... But don't get too hung up on the whole clear plastic thing, really does nothing to improve performance.
PWT makes the best custom backups in the world. I used to work with both Gary Strickland and Gregg Martching from PWT.
If you can't afford PWT you may have better luck making your own. A little time consuming but with the materials available out there not really that hard.
Take a look at these guys too
http://www.weldhugger.com/ You can use there stuff or make your own very similar or a combination of using there stuff with customize attachments.