I'm a huge Black Licorice fan, and Mount Bakers is pretty great. But after I used a tank of it...I realized that I don't really like vaping the flavor for some reason. But I'd start with them since it's cheap.
And you don't need to do any DIY at all (I still haven't ventured into it) but you can get "burst menthol drops" at places like Niquid.com where you literally just drop 1-2 drops of menthol concentrate into a tank when you're filling it. This stuff is super strong, but it'll give you what you're after I think. Just be sure to read how many to do per tank and use cautiously; in the sense that it's sometimes too much menthol. Just research some menthol threads on here- I know there was one recently where people where talking about other versions of the drops that will make anything menthol. Good to mix with any flavor.
Oh, also just to note, BL is what I consider a tank commitment. The flavor tends to stick around even after a good wash, so you'll probably have to soak in vodka overnight to really get rid of it. Just a note before you put it in any old tank. Best of luck.