I agree that the guff clubs won't want to pay that and a player is only worth how much clubs are willing to pay. However given the craziness of transfers these days, nothing would surprise me. Guff teams see Scotland as a cheap market. If McKenna played down there he would be expected to cost over £20M these days. If Tierney had gone to Arsenal for £25M we would expect something nearer that figure. However as neither of those things apply we will probably sell for 6 or7 when I think we should hold out for double that