Yesterday I found a used pair of Coincident Super Eclipse III speaker. Even it is used, still expensive. I read its specs and says its tweeter is not metal. What is difference metal and non-metal? Other than the tweeter,their specs seem similar to M80. Why are they more expensive? Are they made of gold??

Arcam AVR300
M22ti
QS4 with FMS QS Stand
VP100
Definitive ProSub60