I have a original ET doll. I want to sell it, but am not sure how much it's worth.
If it is truly an original Furby (talking and interacting) and comes in the box which is in good condition, about $40. No box...maybe $15.
It's pretty much all about condition and when you list it, be as truthful as possible. List every defect or flaw or signs of use. It just ends up costing you more because you'll have to pay for the return shipping if the customer isn't happen and sends it back. You end up losing money cause you'll have to give them back all their money, plus the return shipping.
Do a search on eBay for more information.