The total size of all item data for a store like Target can't be much more than what, a few gigabytes? Or at least the "UPC -> Price" dataset. So download the whole dataset each night, if you can't get delta changes to work.
And if that had failed somehow, it would have been noticed immediately upon the new code roll-out.
The internet was designed to be extremely resilient to host/route losses, we've made it so reliable we assume all machines are reachable at all times.
(To be fair, apparently they "do" have this but the dataset is printed on the items and the cashiers had to enter it by hand)
