They would probably turn it around and make it compulsory for sellers to send the 10Gbp to cover possible requests and make even more money. They would probably send it on a disk, unencrypted, which would then get lost or left on a train. They wouldnt send buyer details for fear of the data protection act and would omit buyer names etc. They would suspend your trading while searches and investigations were carried out. All the above are possibilities [looking at the question lightly]
If I thought it would work I would send my 10 quid today.