In the UK to the right buyer you may fetch a nice bit of money for it.
Depending on what club he is with now (Newcastle I think) I would look at trying to sell it to a fan of the club or one of the fans.
If you build it up into a Michael Owen fan site it will probably get a lot of search through traffic and therefore be good for Adsense.
All in all I would say to the average buyer, Reg Fee.
To the right person (and you will have to seek them out actively) It may fetch $xx - $xxx