I've wanted to have whiteboards for every student in my room for a long time, and in laminating all kinds of posters and classroom decor I realized that this was the solution. So I simply laminated plain sheets of paper and cut them in half. (Full sheets were just too big, and not as cost effective.)
For the erasers, I saw that many teachers recommend cutting up and using old socks. (Ewww.) Since it is imperative that boards are erased (to keep the marker from staining them), I knew that good erasers were necessary. I bought 5-9x12"sheets of felt from Michael's for $0.33 each. (I only needed two, but now I have plenty extra erasers.) I cut the felt sheets into 3x3" squares (each sheet makes 12 squares), and now I have a class set of erasers.
For the markers, I am using fine dry erase markers. I bought them on sale at Staples over the summer. (Not pictured, they are currently housed in my classroom.) To store them, I decided to keep whiteboards in the basket under each desk in a ziploc bag, complete with eraser and dry erase marker.
Now that I have this already set up, I'm considering putting all of the supplies my students will need in each bag under each desk. I'm just worried about my supplies disappearing. I'll wait on this idea for now and see if it's absolutely necessary. (As it is, I'm worried about losing the markers. Especially since I have exactly enough.)