When it comes to plastic containers for storage, the recycling numbers to avoid are 3 (I forget which type this is) and 6 (polystyrene; PS). Polystyrene can be a rigid, clear plastic, or it can be styrofoam, like egg cartons. Avoid! The unbaked clay and the plastic will become One.
Opinions vary about plastic wrap. I've had success with the plastic "paper" that the bakery section of the local supermarket uses for picking up baked goods in a sanitary manner. ;^D
Barring that, if you get your newspaper or store advertisements in a clear or translucent plastic bag, slice *that* open and use to wrap clay. Works for me! (The bags/paper are a little "crinkly"-sounding; a cross between plastic and paper is how I would describe them.)
Don't wrap in waxed paper; the plasticizer will be "leached" from the clay.
Cheers, Sharon