I gave up buying commercial juices a long time go, always hit and miss, some juices are great, some too sweet and most just plain nasty. I'd love a certain juice and next time I ordered it wasn't the same taste, that became the norm. Juice buying became a money pit of partial bottles that went to waste. I vape tobacco juice 90% of my day so once I found the flavors I liked I went from there to create profiles.
I have 10-100ml different tobacco's, 5-100ml tobacco absolutes and 4-50ml bottles of assorted other flavors, all steeping or steeped. I don't make any formulas but blend my tobacs and TA's in different ratios to always have different tastes. I blend 30mls at a time, vape it up then either repeat the process or make a different ratio or combo. I use green painters tape on the jug to what's blended and their ratios. I have 6-30ml jugs infront of me with my tobacco/TA blends each with their own subtank or TFV4. Today I have a 20ml HS Highway/grape blend I will occasionally vape.
My wife is a cheap date who vapes only 1 juice, a desert ship/cotton candy blend. I make hers 200mls at a time since she goes through roughly 50mls a week so when its time to cut her juice into jugs I then remix her juice so there is always a steeped batch ready for her.