Thanks to my correspondent, R., who spotted this in El Universal, a Mexico City newspaper: A portrait of Maximilian has been auctioned by Mortons for 450,000 pesos, about USD 20,000.
Almonte was a prime mover in bringing Maximilian to Mexico and, in 1865, he served as Mariscal de la Corte, or Court Chamberlain.
There are probably a good number of these portraits floating about Mexico... I have yet to see one displayed anyone's living room, however.
I wonder what its new owner plans to do with it?
A tidbit of a memory comes to mind. When I first came to Mexico and started work at ITAM, a private university, back in the 1980s, the office I inherited included a large closet, and inside that I found a portrait of Karl Marx. It was swiftly removed by its owner, who taken a better, corner office. He liked to joke that he was a closet Marxist.