Great concept
I loved the 'Thunderdome' concept. Two enter, one leaves... The story was nicely advanced, each trade becoming more and more difficult and the rewards grew. The Vernon Stynes character was annoying and a supension of belief - why would Harry continue on with such risks when that loose cannon is about.
I would have liked to see the woman trader explored a bit further... how would Harry deal with that?
The ending worked, but felt a bit 'thrown on for effect'.