Depends on price....if someone sells 3mls for a $1,50-$2 you can sample a lot of juices from a vendor cheap and see what u like vs $5 10 mls or somethin and its not a complete rip off...its enough to last a half day. I wish there was more 8-10 3ml sample packs. I like build your own sample packs best.
Your business your price, but I tried almost all ..... flavors because they were $3.50 for 10mls being there smallest size. $21 for 6 flavors and 60mls of juice is a great deal....
I think the easiest way to do that is just sell one nic level for samples (and have a bunch of premade samples so it could be made in batches...my 2 cents....