I did a Google search with your upper control arm part number, 107-330-14-07, and found only OEM control arms....and as you noted...they are pricey. I did find a source for less than the price you stated. PM me if you're interested.

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'89 260e (212K Mi.), '92 400e (208K Mi.), '92 400e (not a misprint) (146K Mi.), '95 C220, '81 240D--Sold