First, no oil.
Second, alcohol is okay as most flavorings/extracts have alcohol in them already. After making your
e-liquid let it sit uncapped overnight for the alcohol to evaporate.
Third, head to Wally World. Go to the spice aisle. Look for Watkins flavorings. There are quite a few that do not contain oil. Then head to the arts & craft area and look for Lorann flavors. Wally World has the 2-packs of the little bottles for $2 or so. They might be in the main aisle or on an endcap hanging from a cardboard box display.
Wally World has other Watkins flavors, but I didn't need them. They also sell McCormick flavors but they're more expensive. Watkins is about $3 for a 59ml bottle.
Finally, you can also buy small 7ml bottles for flavors from diyjuice.com. They're the sister site to Flavor West. Each bottle is only $2.75 and $2.85 for shipping. I like them because I can try a small amount flavor first.
Making your own e-liquids is an addiction unto itself.