Woot! I found one I could buy - posted here for others contemplating something similar:

http://www.sportsimportsltd.com/inseluinairc.html

Edit: I found one that is supposedlyt better (keeps the air for longer):

http://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=32328&SortOrder=1

Last edited by AQM; 07/03/12 08:44 PM.