Unfortunately it seems the US Mint Deal has, like all good things, come to an end.
The US Mint now seems to call the coin purchases "cash advance" and thus, if you buy coins on credit you will be charged 3% and daily interest starting on the day the purchase posts. There have been mixed reports but if you do a coin purchase, make sure to read the fine print and don't buy them if it says "cash advance" anywhere.
So obviously it's no longer a cost-effective way of fulfilling your minimum purchase requirements.
Not to worry though - there's always a deal out there and we'll make sure we'll let you know when we find one. :)