I found them at the local auto parts store. They're an aftermarket thing, were on the shelf with the other performance parts (such as there were--I live in a pretty small town). They're a generic set, so didn't need the usual year-make-model. Helped that the guy at the counter was (no offense) an older chap, so he remembered folks with imports buying these sets back in the day.
The key is 7mm solid core. Brand doesn't really matter. I have the side entry cap, so I just cut the wires to length and away I went.