@4_bathrooms makes a very good point. If you don't have a Collection In Person option on the listing and you just leave it as it is and allow the buyer to make payment for the item then not only could the buyer open a false Item Not Received case against you and get a total refund of the money paid as a result of the fact that you would have no way of being able to provide tracking details to prove that the item was posted to his/her address and get the case closed in your favour, but you would also end up with a defect on your selling account as a result of eBay closing the case in the buyer's favour and forcing a refund.
In light of the above if the buyer hasn't paid yet revise the listing as advised and add a Collection In Person option to the listing, then ask the buyer to select the Collection In Person option when making payment for the item. That way you can get around the problem of the tracking number, as you will not need to provide a tracking number in the event that that buyer selects the Collection In Person option.
Even if the buyer isn't out to scam you and doesn't end up opening a case against you, it will take longer for you to get the money from the sale if you just let the buyer pay for the item via the postage option that a buyer would use if the item was to be posted to his/her address, as eBay require tracking that shows that the item has actually been delivered before releasing the payment. Without tracking to show that the item has been posted you would have to mark the item up manually as having been despatched, as you would not have a tracking number which would automatically trigger the Item Despatched function once entered. However, if you revise the listing and add the Collection In Person option to it before the buyer pays for the item you can avoid all this palaver.
