Thanks for the great ideas already shared! I was thinking the foam in my boxes would need replacing sooner rather than later & I'm sure I will prefer foam with slits as apposed to pearcing it all the time.
Any sort of silica-based dessicant should work well assuming the ambient humidity where you store them is on the low side. You can also try 'baking' out moisture before use...
http://www.google.com/products?q=silica+dessicant&hl=en
For the 'brave'... Possibly a lifetime supply? http://www.petsmart.com/product/inde...uctId=11256828