Delivery
Shops post their own parcels, so delivery is set per shop rather than by the marketplace. The cost and the estimate both come from them.
Cost is worked out at checkout
Delivery is priced once we know where the parcel is going, so the listing page does not quote a figure. The full total, delivery included, is shown before you confirm payment.
When a delivery date is missing
A listing only shows an arrival window when the shop has given production and postage times. Where that is blank, the shop has not stated one — ask them before you buy if the date matters.
Separate parcels, separate tracking
Items from different shops travel separately and each gets its own tracking number, added to the order once that shop hands the parcel over.
Made-to-order takes longer than stock
A printed item is produced before it can be posted, so it leaves later than a stocked one. That production time is part of any window a shop quotes, not something added on top.