It depends on the condition. I have one for sale for $1300. Needs only refinishing. Plays well. Completely rebuilt they sell for $25,000.Doyle Fowler drtexas@yahoo.com
Depends on the model and condition it's in. Do you know the serial number? From that you can determine the date. If you measure the piano, then you will know the size and can determine the model.
Depends . .the Knauss (Coblenz) are about 450 Euro'sthe Knauss (Made to the Emperor of Gemany) are valued 'round 750 Euro'sBoth would be in a less condition, but playable.