I did find one with an SPST switch in stock at Digikey for $9.64 plus shipping. Somewhat surprisingly to me, they have 757 in stock. Mouser is out of stock and quoting 23 weeks lead time!
Since my scope is in the US and wired for 120 volts, not 240, it's not really necessary to disconnect both sides of the AC line from the power transformer, only the hot side So this one will do unless I can find the correct one.
