That's the key to it isn't it you don't know enough to take an informed gamble as you say its a widely faked brand I would leave it to others on this to take a possible costly sting on the off chance they can make a bit of money off the back of a charity organisation, and make a mockery of the word goodwill, and that's what some people bidding on this are likely to be thinking how many notes do I drop on this in the hope of making X amount in return.
Don't get me wrong I love a bargain from charity shops I am a bit of a skinflint when it comes to shopping every pair of jeans I own has been bought at charity shops, if you need a Corum (if indeed that's what it turns out to be) in your life then go for it but only to the amount you are prepared to lose on it don't get carried away.