Getting an account backordering = $0
Winning the MSNHotmail.com = $200-$500
Watching the look on your face when MS sues you = priceless
There are some things money can buy..for everything else use your common sense.
I am not a lawyer and these are only my personal opinions. If you require legal advice, you should seek qualified legal counsel.
IMO, the registrar catching the domain could certainly be held liable if they are parking the domain and generating ad revenue while it gets auctioned off.