I have seen a few of the Elymais tetradrachms

. They are from a quasi-independent kingdom of Parthia. They are often described as billon but often appear to be bronze, I am sure this is because of the extremely low silver content. The often depict a king in front facing or profile, with an extremely weak and or non existent reverse. These coins tend to be rather expensive for such a "weak" coin.

Usually in the $150 - $350 USD price range. Are they exceptionally rare? I can't imagine them being highly sought after as they are relatively unattractive and the history surrounding them is less then front page. I was planning in the future to pick one up as I have been consumed by the collection sphere of coins of the "other guys."

Maybe you guys can guide me in the right direction.

Maybe I am well behind the

on these...
Any thoughts comments or opinions would be much appreciated.