Yeah it depends hugely on what you want on there. I mean the guy could have been lucky with that plate at the time he bought it. But they pretty much range from £250-£1000 easily. If it is that short (b3 bat then it's probably a grand, if he'd gone for E77 BAT or so it would be closer to 250, but who the hell would want that plate. You could always buy a car in Canada with a personalised plate and get it shipped over here!
Feels like it's Canada here btw, weather is brrrrrrr.