Yeah, I've always regretted not picking up the Rivendell rain cape when it was available.
Similarly, really annoyed that the Brooks England John Boultbee Criterion Jacket was a limited edition and that I missed out on the tin cloth hunting/dress jacket Filson offered a couple of years ago.
Mostly I just wear an old cotton safari jacket, though I did pick up a very nice one, a "Deluxe Safari Bush Jacket - Khaki" from Historical Emporium --- unfortunately, I find the extra length on it a bit annoying, so don't wear it as much as I'd thought I would.
I keep thinking about buying a Brooks England rain cape, but mostly I plan ahead and don't ride in the rain, so hard to justify.