I guess the most expensive one I've seen was the one which claimed to be new, unused and in its original box. However, there was a bit of a joke running on here about whether there was actually a C5 in the box, or a dead rabbit or just a pile of rubble etc... Anyone else remember that?
The owner I think wanted more than the £1,200 that Adam Harper charged. Can't remember exactly how much the Ebay seller wanted for it now, but I think the price you've seen is something close to it.
What condition was the Garage one in? They clearly haven't done their research and just slapped a price tag on it. Anything's possible.