[Arran]

Ed;
I used to get packs of grommets from some auto parts stores, it's been a while but they were less then half that much, for more of them. Grainger and McMaster-Carr are two other places to find stuff like that. Getting back to the hot chassis design, I think if it works well on an isolation transformer then you probably could rewire a chassis to make it float, basically for shielding and RF grounds, the trick is to find the minimum value of capacitor that will couple the chassis, and B- together, but block most of the voltage.
Regards
Arran