Don't just cancel, of course the majority of buyers don't want to spend a fortune on delivery so just send them an invoice with $70 or whatever then they either pay that or they get an unpaid item strike.

If you want you can go on line and find out how much it would be using pack and send as they pack the items up, just quote that cost plus a few extra for your trouble and then if they do happen to want it enough to pay you don't have to do any packing.