I never use paper liners. They stick and make a mess when taking them off of the muffin/cup cake. More often than not, you end up losing much of your cup cake to the liner!
I use a shot of non-stick spray in each cup. The cupcake base browns a LOT better, has a better texture, and the cupcake looks prettier.
But, in response to your question, liners can be found in the bakery dept, usually near the sugar, baking nuts, birthday candles. Once in a while they put them with the foil and plastic wrap. When in doubt, ask a clerk or manager. They are there to serve you.
"Food is our common ground, a universal experience." - James Beard