This image, from Retro bike, might help. I understand why people don't like them, but I've had them on a few bikes without too many problems. These Deore's seem to work okay. Is it the "boss cap" you broke? It it, by chance, the same model of brakes as this? If so, I actually have an extra boss cap.

Only thing is I live in Canada and it could take the mail a long time to get to you. PM me and I'll mail it to you if you could use it.

And , yes, I think some BMX models can serve as replacements. At least I did use a BMX replacement on one bike I had, but that was a long time ago, and I don't remember the details.