Rob over at Goodprophets.com is a good one. Not sure if he still does it, but he would throw in a free 30ml to every new customers, your choice of flavors. And more than once, he has sent me free juice to try. Once I told him I wanted to try Cocacola, Chocolate or Cappuccino and he sent me all 3 in 30 ml bottles. I am sure he can't do this for everyone, but I can attest to his generosity. He's always been great to deal with and I always get my stuff in 2 days.
Could a supplier take 5 or 10 empty carts and fill them with different flavors maybe at a low or medium strength? That way I could try them without buying a bottle of each one. I'm guessing if they did this at cost, a sample pack would only be 6 or 7 bucks.
Right now Im getting all my juice from the same place I get my other supplies. Its just too expensive for me to try out a bunch of different juices.
If a supplier really took a chance and just mailed out some free samples they might end up with a lot of new loyal customers. Maybe cost wise its too expensive, just a thought.