The cost would run in the millions ... sometimes brand name is much much more expensive than the actual property that brand has.
Although Amiga today is not what it once was the name is still a very good one (short, easily recognisable, etc).
Someone selling the brand knows that who is going to buy the brand name wants it because he can make lots of money out of it because of the reasons explained above ... it is how much the brand name is sought what determines the final price.
At the moment there is a legal issue on the name which implies that the name 'Amiga' is still sough after!
