Some options:
1) Imsto's website
2) GON's website
3) LZ's website (Maybe? I know he had them offered with some other GBs)
4) Old Cherry boards
5) IvanIvanovich's GB
6) Classifieds
7) DIY
8 ) Zeal's GB
I have stabilizers from harvesting old Cherry boards for parts, the classifieds, and one of LZ's group buys. I've also got a few coming from Ivan's GB. They're kinda hard to find to be honest.
Someone in the community can step up and make a bunch of them by hand or contact a manufacturer to have them made. Then GB or sell them for retail.