I have been thinking along similar lines to this, but was struggling to find anywhere that sold the right materials.
Out of the blue -(while searching for something completely different ....... naturally ), I came across this:
The first one is a magnetic plastic sheet - the second is a magnetically receptive sheet - in other words not magnetic itself but something that a magnet will stick to. I guess if you are using self-adhesive magnets on your bases you'll only need the second one.
The company offering this stuff don't do the printing, but they can arrange it for you if you supply the artwork and will ship it as a completed product - if I understood the sales person correctly the artwork would be printed on a separate vinyl sheet and then bonded to the magnetic material.
I'm awaiting a quote so I'll let you know what it comes to.
Edited by Funkleton, 22 July 2014 - 02:15 PM.