I used prints of my art cards to place. An art card or art cards editions and originals, (ACEO) are affordable, collectable, and tradable. It's like creating your own virtual gallery. They're very hot in the selling artists (like me) circles. I place mine in a trading card sleeve to keep clean.
A good source for something like magnets is Zazzle.com. A magnet, retail, is $1.95, but if you create it and buy it, it is cheaper than buying something in another's Zazzle store. Buttons are $1.45 and stickers $4.95 for 20. Again, cheaper if you do your own.
I've been very pleased with the quality of their products. I can recommend them.
Chris