Sunderland paid £9million for Gordon in 2007.
We need to lose this idea that we can't hold out for a big fee because teams won't pay that for a Scottish player. It's only relevant if we cave to the first offer. Lower league English players have been selling for silly fees for several years now.
Our bargaining power is not based on who we are as a club and we are not under pressure to sell our most prized asset. The fee is based on what McKenna is worth to the buyers which informs what they are prepared to pay. If he was a highly rated EPL defender he would be worth much more than £10million...£20-30million is nothing for a proven player these days.
If they think McKenna is the real deal and he's not just a speculative signing then we should hold out for the going rate. Ideally we should be going into negotiations with more than one club interested.
I don't know if we'll get £10million but I will certainly be disappointed with anything less than £5million and a sell on clause.