Welcome to Namepros Mike.
When the domain name is a personal one, like this, the value depends entirely on factors like: how many people have the same name, how badly they want this dn from you, how badly you want to keep it, and other things... like if any of the other Mike Walkers are rich, ha ha.
This is your name, so be VERY careful of selling it. If you like to develop other kinds of sites, and having a personal name site really means nothing to you and you don't think it ever will, then you'll probably sell. Otherwise hang on to it - as the reply above says, you would probably never get it back if you sold it, unless you were to get rich in the future and make the next owner an offer he couldn't refuse.
If you're short on cash and absolutely have to sell this for some $$, make sure it's for a good amount. You have a dn that's based on two good, common names, and I'm sure there are a LOT of M W's out there... and every one of them would like this domain name. Don't sell your name out cheap, if you can help it
Think very carefully about it. No one here can accurately give you an appraisal of its worth; that value has to reside in your heart, so to speak. Peoples' personal name dn's are a little different to valuate than other kinds...
