Those notes at the bottom of the page are referenced in different rebates and additional discount promotions in the various 'click for details' throughout the web page. It is not related to whether the credit union / supplier pricing is still valid.
Not expiring, but I note that the "build and price" page has been redesigned. Discounts are still the same, but before, it was rounded off to the nearest dollar. Tonight, when I resubmitted my build, 20 cents came off the new price, and identical to my MacMulkin price. I guess the page no longer rounds the price to the nearest dollar.