I'm pretty certain the clicker plate is the same as for the Helix, Nexus etc.
I had an Avalon which had silver (non anodised) clicker extension plates (3 sizes). When I sold it I couldn't find the two that weren't on it at the time.
Later when I got my gold Helix, I found them and thought they looked much better than the anodised black clicker plates that come with the Helix.
So, someone might have one or more kicking around you could have or maybe a retailer carries spares?
Simon