I had a similar situation with a buyer but they did ask first. I sold some clothes hangers which are a pick up item and they line in NSW ( am in Melb). They said was it ok to purchase and pay then pick up when they come down early October.

Now I don't mind doing this because they paid first. As long as they pay now and you can tell them you will hold it for max of 3-4 weeks. If they do not pick up or contact you you can then refund and re-list.

Give them time to truly to you as they only just purchased this morning and they might have gone out for the day.

Cathy