A fiarly high amount as I recall. I think there is a demand coming from Asia as well at the moment.
The amount it is worth is what someone will pay for it jn a free market.
A big auction site is not a bad place to watch and see what they go for (as Peter said). At that point you'll know what price range to ask for, or set a reserve at. Don't make the mistake of seeing a high asking price and thinking that it sells for that, watch for completed sales, asking doesn't mean selling.