I ran into a similar problem with some PC big boxes and press kits
I've found something like these might work
http://www.ebay.com/itm/350992245273...84.m1439.l2649
http://www.ebay.com/itm/221229384360...84.m1439.l2649
It's a little hard to figure out what will box shaped items will actually fit into what size so it usually does well to get multiple different sizes
I would actually recommend getting ones larger than 10" by 13" or at least wider than 10"