It's actually a rather complicated bracket, multiple bends and folds. yamiya has them new for $65. So many people did to them (me included) what was done to other parts like exhaust pipes. Took them off and pitched them in favor of moving it up on the handlebar. The switch itself wasn't waterproofed for use in that position and many have since failed.
Seems the preferred location for those of us restoring (me included) is to put it back under the tank. And with a dearth of brackets... hence the strong pricing.
I've noticed a few have said it went on the downtube, which isn't exactly correct. It goes on the horizontal tube under the left front of the tank, not the downtube. And there is not enough wire in the stock switch to put it on the right. Left side only.
I think a Gordon frame kit would interfere. I had to make my own bracket to run my APE frame rail kit.