I feel wealthy, I've stockpiled three of them. Don't ask, I'll never part with 'em, like hen's teeth when you need one.

Another conversion option is a threadless 1" BMX headset, then you can use a 1" threadless fork and 1" or 1 1/8" stem. Only one problem, the 1" threadless headsets aren't in production anymore. I found a few from porkchopzz4 on the 'bay. $20 ebay cyclocross fork completes the deal: