New T&C's from the mints website:
"There is a 4-box $1 Coin limit for every 10-day period on any and all $1 Coin orders. Beyond that your credit card will not be authorized. If you need quantities greater than this, please send an e-mail before placing your order to directship@usmint.treas.gov explain why your order should be exempted from the limit."
There have been reports that this limit is per household.
If the 10 day limit goes by order date, shipping date or CC authorization date is still unknown but time will tell.