Brian: fair and amusing post -- point accepted.
I am less convinced that the ongoing ownership costs of a used M3 will be less than a comparable used AMG car, esp as the miles add up, but there are probably not that many 75,000 or 100,000 mile+ AMG cars out there at the current time to give a very valid comparison given the fact that far fewer AMG cars were built than M3s and the AMG cars began to be sold here only in '95.
Much of my [probably, given the paucity of evidence] prejudice looks to the generally accepted better durability of M-B and the relatively higher proportion of older models still running and looking good -- but we all know that the price thereof is regular and meticulous maintenance!
'98 C43 AMG
'93 190E Limited Edition (including factory Sportline package)