Be careful with your choice of digital scales ...
Best to have accuracy to 0.01g but if you want to mix 200-250mls of juice they also need to cover that weight range. No good if they only measure up to 100gms.
I've ended up with two sets of digital scales, both cheap from ebay ... one's accurate to 0.01g and tops out at 200g ... the other's accurate to 0.1g but will measure up to 1kg
If I'm mixing more than 100mls, I use the most accurate for measuring flavourings, and then switch to the other when adding the diluents.