Hey Galandol, This is were you can make some money. What you do is put a high price on it, and just sit on it until you see more of them being sold. And hopefully you sold it for about the right price.
Example : Had a Bronze Cluster, which took me about 2 weeks to sell, I had it 1gp, and someone offer me 80 sp, I made money so I was happy. Then 2 days later I saw a Bronze cluster sell for 50sp and other times see them selling for 2gp. So it is up in the air and you start the value.