whats a fair price for a secon hands cassina LC6 table  

Hi everyone,
I have kind of a straight forward question, what is a fair price to ask/pay for a second hands in good condition Cassina LC6 table (standard black version with see trough glass).
I'm hoping someone could help me out a bit here, i'm really not a connoisseur on this stuff but i recently moved and i'm buying some second hand furniture. I have the chance to buy a cassina LC6 table but the seller doesn't want to name a price and asks me to do him an offer.
Hope someone here could help me out a bit, it would be greatly appreciated