Yep, I'd looked everywhere for them (craft stores, Walmart, etc.) before I saw somewhere to check the pharmacy. I've asked at 3 pharmacies and all 3 had them. I get mine at Giant Eagle pharmacy. The small bottles are just over $1 apiece. Fun to experiment without spending much.
I think all of the flavors where I get mine are water soluable. If you look at the ingredients it will say if it has oil in it. I don't know about the spearmint, I've never checked it.
Someone else may chime in here. If not, start another post just asking if the spearmint is okay to use. Did you try a search on this forum?
And no, the oils are supposed to be bad for atomizers.