When our stocks run out, normally I dont check them because, why not? But it doesn't alert you when your chest is out of items, it just alerts you when someone tries to buy it. Also, please try to give names for shops instead of Coordinates for the OOS notifications, heres an example "Shop: 1 Diamond for 4 Grass is out of stock!" And if we get alerted while we're offline, have it alert us when we log back in.
That would be cool, I don't think its possible tho since the shop plugin we use is not made by skyblock developers, so I think it's pretty difficult to add features / edit it.