Suggest you buy here. I've bought from this seller before. Good prices, genuine parts (no aftermarket crap) and fast shipping.

http://www.ebay.com/itm/Mercedes-Benz-Transmission-Filter-Gasket-Kit-Genuine-Original-722-6xx-1400095-/251463835791?pt=Motors_Car_Truck_Parts_Accessories&hash=item3a8c69a08f
This is the filter you need (compatibility chart data in the listing is wrong).