I got one on eBay for $85. There really seems to be only two types: one for the M103 and one for the M104. Either that, or I totally lucked out and randomly got the right one.
The picture on eBay looked like mine, so I went for it. It was a Lemforder brand, an MB OEM.
Pulling the radiator takes maybe ten minutes and saves an hour plus skinned knuckles on radiator fins.
HTH,