You can make a wonderful (and quite large) magnetic bulletin board from a steel drip-pan from the Auto Parts store ($19). Just spray the bare metal with a spray adhesive then cover with fabric that matches your decor OR, cover with 2 layers of black landscape cloth, like I did. For a smaller version, use a steel cookie sheet from the dollar store!
I'm wondering if it could also be made with an old cookie sheet (non-aluminum). One can find old rusty ones cheap.
They sell the magnetic strips and spice cans at Ikea for real cheap! Great idea for kids room!