---

@michellebartley wrote:
And if seller does a manual invoice then you are obligated then to complete the transaction so its in their favour to do a manual invoice because then its a binding contract.

---

The contract is formed as soon as you confirm the purchase, so with or without a manual invoice, you're obligated to complete the transaction once you've purchased an item.

That aside, a seller can't combine items if they have immediate payment required because you can't buy them without paying for them, which is most commonly the reason a seller will instruct a buyer to buy / pay for items individually - not being able to provide combined postage discounts is one of the primary reasons many sellers don't use immediate payment required, but for other sellers it eliminates a lot of problems if their buyers rarely purchase more than one item (if their items are suitable for automatic postage discounts and they were set up, adding the items to a cart should mean the discounts are automatically calculated before checking out, but at the moment the cart sometimes won't calculate these discounts).

If the seller's items do not require immediate payment, there's nothing stopping you from committing to purchase each item, then requesting an invoice from the seller in order to pay.