Flavorings for e-Liquids are mostly based on certain brands of food flavorings. You can purchase those online or from some confectionary stores.
Popular ones include:
- Lorann Oils
- Lorann from Totally Wicked
Important note about flavorings
Some flavors contain oils which will make vaporization less effective, like those flagged ** on Totally Wicked. It is better if those are avoided, or if you really want to use them, use a very little quantity in your mixes. Those flavors are extremely powerful and strong anyways, so in any case, a minimal quantity is needed.