Oh, those dice ones are sweet? How much for six or eight units?
That might be difficult if you want them the same... I got those dice from a grab-box of sorts at a convention, and I'd have to do some real hard looking to find more... I have maybe three more pairs of the same design, but that's about it... I do of course have other styles of dice that I intended on turning into USBs however.
As for a price, I'm thinking about $30+shipping each. This is based on the stock of USB sticks I currently have (8GB sticks), the relative rarity of the dice from my supply, overall material cost, and of course labor. If I run out of USBs, dice, etc, costs will probably change appropriately.
I've never had to mail anything internationally, but these are quite small, so I don't expect it will be too expensive.