Sorry, for the confusion earlier, you had me wondering if someone had swapped an MK5/6 mirror and rain sensor base onto your car???
I'm pretty sure I have (I'll check garage Saturday) an all grey that will fit the windshield mount you posted above. I may have created something all black that uses the mount as well.
PM me an email or cell and I'll send pics tomorrow. Whatever I have will be much more affordable than $300, most likely a fraction.
Thanks