Undecylenic acid should be easy enough to obtain. Thorne sells it as SF722, and Dr Jeff sells it as Candida Force. (Candida Force = SF722 = undecylenic acid = 10-undecenoic acid.) Worked great for me.
Regarding niacinimide... I just checked my B complex (max stress B) and under Niacin it says "Vitamin B3 as niacinimide." WOO-HOO!!