estimate value of a grand Grotrian-Steinweg?

[zephyre]

hello,

i'm thinking to sell my 220cm grand Grotrian-Steinweg, built in 1939 and in good condition with most original parts (strings, hammers etc). the hammers are rather worn down and the sounds it somewhat brilliant. the wood is dark brown. ivory keys. situated in stockholm.

anybody could give me a hint on a market value?

best,
mattias