I've been to Manheim auctions. A friend of mine and I were operating a used car business for a time as a hobby. I bought my first R230 there.
I don't know the answer to the original poster's question, but I can say that it was my experience that remarkably, Manheim prices were only a small discount to what dealer's were selling Mercedes for on eBay. So eBay can give you an idea. Further, you can go to New Car Prices and Used Car Blue Book Values - Official Kelley Blue Book Site and see what dealers are paying for trade-ins. I would guess that the Manheim prices are about 10% higher.
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