The hardcover collecting Original Sin will no longer be $49.99 as solicited, but $75. retailers are being given a week to adjust their orders, but they might consider making an advance order from Amazon instead.
At 55% off the cover price, this is a significantly higher discount than retailers would expect from Marvel and Diamond, and with free shipping, any retailer would do better to order from Amazon at this price rather than Diamond, and Amazon itself would make a loss on this price.
It is likely that the price will be changed soon. But Amazon are usually good at honouring such deals.
It may be even cheaper for foreign buyers to take advantage of this deal, compared to, say, the Amazon UK price…