Meh, I'm pretty sure 'value' is irrelevent before the fact its 'property' (parts of data). Once its property, all the judge is gonna ask is 'whats it worth?'.
The thing is. The judge will ask not you. The judge will ask an expert witness, probably invited by claimant. The expert will pull out mobile phone check current mtgox rate and say "As of this moment this day and this month of year 2012, based on current exchange rate on leading exchange, which is 356.33 $ per 1 BTC, fair market value of 512 BTC can be estimated as USD182440.96".
Numbers could vary, but you got the idea.
So called "expert witness" testimony has little value when the either the plaintiff or the defendant provides the "expert". They could be getting paid to testify in which case they will say whatever the person paying them wants them to say.