Most B&Ms have cartos prefilled with the juice they sell. You can go in with your 510 device, and you screw in their carto and use you own tip. Try different juices. You may find one you like. If you do, buy it. If you don't like, don't buy it just because they let you try it.
I go to 3 different B&Ms for juice I like. The other 30 or more the each have to taste, I don't like. I just don't seem to like a lot of juices, or they don't sell what I like. There are a couple of more stores in the area I will try. For now I have one juice in a Protank II, one in a Mini Davide Glassomizer, and one in a sandblasted Phiniac tank.
As finicky as I seem to be, I don't want to start ordering juices on like and not like them. That would be a waste of money. I did a sampler kit once, and didn't like any of them.
One of those B&Ms was going to stop making the only juice they have, I liked. They keep making it just for me. So I buy 30ml, every 2 or 3 weeks.
Greg W.