I got the same clamps as listed on e-bay for $35 shipped, and had them the next day! VTwin Mfg part# 31-9920
http://www.biker-direct.com/exhaust-mufflers/clamps/muffler-pipe-clamps/smooth-style-exhaust-clamp-set-for-1-3-4-mufflers-or-extensions
Kuryakyn "Longhorn Dually's" w/ 1" clamps. Part# 7890. Should have taken the set off my last bike, but didn't. So now It'll run me $120 for another set.
Any chance it's balanced with some form of "beads"? I haven't experienced the issue, but I've hear others say it's possible for a bead to hang up in the schrader valve / stem.