I agree with what everyone else has said. Buy smaller flavors, and more variety. Buy big sizes later when you know what you like. I'd nix the beaker. Pg and VG are so thick that transferring stuff from a beaker would be a pain. You can lose a couple of ml just from stuff sticking to the sides, or you can stand there for 10 minutes holding the beaker to try to get as much of the liquid out.
I mix in bottles, even batches as large as 60 ml. For big batches I use large 20-30 ml syringes, so I can push all the liquid out. If I need more than will fit in a 20-30 ml syringe, I will just measure twice (i.e. If I need 40 ml of VG, I use the 20 ml syringe twice).
i also agree on getting a dripper. To change the flavors, you can either drip some unflavored and vape through it, or just drip your new flavor a few times till the taste from the old disappears. I think with a dripper you will have to learn how to rebuild though (if you don't already).
Before I got a dripper, I would just fill a protank with about 2 ml of my juice I was testing. I figured 2 ml was enough to give me a good idea. If I couldn't make it through 2 ml, I labeled the juice as 'unusable' and dumped it, rinsed the coil, and loaded up another to try.