There are quite a few sites to go on, and some of them have already been listed.
The fairest and easiet way to distribute them is to put numbers (how many children you will have in the class) in a bag and have each child pick a number. Place the placemats in something big where they cannot see them have them reach in and take one, starting from whoever has number one. Then what they get, is what they get.

I would think for sanitary purposes, you would want all vinyl. Little hands are not always that clean... :D:D:D