Some people are just fucking morons.
The other thing is people who piss and moan about postage.
When I sell bulk items, I charge the cheapest cost possible, and you still get people complaining.
I just tell them the weight of the item, and tell em to see if they can find it cheaper...they never reply.
I purposely list big sets as UK only, but in my auctions it states that international bidders should contact me first for postal costs.
I still get international bidders bidding without contacting me, and I always email them before the auction ends to tell them the item was listed as UK only because of the postage costs, but if they are willing to pay them, I am happy to ship abroad. They nearly always pull out when they realise how much it will cost to ship to them.
