Well because it can be posted in this forum, the flavors are only $1 more per 5 pack than the blanks. Basically like buying blanks and getting a 5 ml bottle of juice for $1. Even if you don't like the juice you can spin it out and give it away. And because I saw your post about refilling spun cartos and still tasting them, squirting hot/boiling water through them with either a syringe (no needle, squirt through the rubber cap) or a turkey baster (through rubber cap, or use a small piece of tube or rubber grip from a pen as a baster/carto adapter). The most lingering bloog flavor I had was the mint, and about 5-10 squirts had it undetectable.
So you may have found similar, even cheaper blanks via PM, which I likely have tried as well, but considering you get 5 ml of bloog juice with their prefilled, IMHO the $ is pretty close.