The median asking price for a used one is $9.99, across 1 live eBay listing for the 1980–1983 generation. That is what sellers are asking, not what buyers paid. Sold prices are not published in a form anyone can measure at scale, and an ask read as a sale runs about a quarter high — so this says which one it is.
That depends on what the yard charges for it and how long it takes to get off the car, and on where it sits against the other 18 parts on a 1981 BMW 3 Series that have a market. The full sheet for this vehicle ranks all of them by what you save and by what you clear.