I've gotten some from The Perfumer's Apprentice (here: https://shop.perfumersapprentice.com/ https://shop.perfumersapprentice.com/). They sell scents as well as

I've gotten some from The Perfumer's Apprentice (here: https://shop.perfumersapprentice.com/ https://shop.perfumersapprentice.com/). They sell scents as well as flavors. Most of the flavors come in 4 or 15 ml bottles and only cost a few bucks each. You do have to play around a bit with the concentration though--some of the flavors have a narrow range where they taste good and not too subtle nor too overwhelming and fake. We made a pretty decent clone of a pumpkin spice latte, plus some other dessert-type stuff.