Sorry for initially tagging you before I edited my post, H_R, I was looking for your thread.
It really is astonishing how poorly WM's site is run given that they're such a large retailer.
If you still have it in cart after all this time, you wouldn't even need to mess with the API. WM pulled the listing to prevent add to cart but if it's already in cart, the quantity can adjusted and use WM Plus for free drop shipping. You can just play with tabs so you'd always keep a quantity in cart.
Anyone else remember this bundle being $2.17?
This is probably off topic though. Apologies.