Yes, 1/8" triangle exists. I have some purchased several years ago from my LHS, though i do not know the distributor. A quick search does seem to indicate that it's hard to find...I'll see if i can track some down.

As for leading edge stock, as mentioned above, any airplane-oriented LHS probably has, or can get, some of many different sizes. While I echo Ken, and tend to shave/shape/sand my own, I understand the preference for using "pre-shaped" sticks.

If you can't find some locally 9always preferable), Sig has some listed on their website in 3 sizes.