I dont sell mine but i will trade. I considered selling my liquids after many people asked me to but the market is so saturated that i believe i could only take it so far.
I mostly give my liquids away to friends and family. I have sold a few bottles but only if someone is interested in buying 4oz or more, it isnt worth my time to mix up a 30ml bottle. Now if you have a cake or cookies i like ill gladly mix up 30ml to trade, hehe.
Break out cost per ml for each ingredient.
Multiply amount of ingredient by ingredient cost base.
Take a weighted-average of all ingredient costs.
Multiply by, say, 5-10% for variance (often when mixing there is loss here and there, inaccurate measurements, etc)
Add together. These are your variable costs. This is what it the ingredients cost to make a batch.
Don’t forget your fixed costs. Remember that you pay shipping when you order, perhaps you use syringes and throw them out after mixing. Also, that juice goes in a bottle, possibly with a dropper. Allocate these costs to each bottle.
Decide on your profit margin, and don’t feel like you’re being greedy by profiting off this sale. After all, you are creating the juice and providing a product. It has value, which is why people want to buy it. In addition, you spent time/money researching and developing your flavors, which resulted in the value of your juice.
Record these costs, expenses, and revenues. You will need to report these to the IRS (possibly as hobby income).
Be glad you have created a juice people are willing to pay for.
Be aware, though, that if you are too cheap you are going to be spending lots of time making juice for other people for very little return.