As you probably know,
AttackXp.com is available. So its worth is pretty much in how you develop the site.
I am a n00b so don't take me to seriously. But i recon low $xx if not reg fee. This is only the domains intrinsic value IMHO.
However developed, could be higher.
Can i suggest something,
AttackWindows.com
much better!!!!
Still im pretty sure like destroywindows.com and multiple other things like it are availible so its all in how you develop the domain