I spent over an hour looking for two different blueberry concentrates I bought about 2 months ago (I think from Capella and/or FlavourArt) and I STILL can't find them, so I used some "The Flavor Apprentice" blueberry I had and I think it really came out well. In fact, I like it better than the High Caliber Blue Raspberry, but remember that taste is subjective, but I think you can work it to how you might light it!
7% TFA "Blueberry Extra"
5% FlavourArt Raspberry
4% Cotton Candy (this came from Health Cabin a long time ago, but I think any brand will do -- it is just a great sweetener)
Good luck and let us know how you come out with it!