The scene in "Letter to Santa" in which Donald Duck and Uncle Scrooge (dressed
uncharacteristically in a suit jacket and tie) hit each other over the head with sacks of money as if engaged in the world's most expensive pillow fight certainly demonstrates great wealth, but as it occurs in the privacy of Scrooge's own office, it's hardly ostentatious.
This panel from the last page of "The Great Duckburg Frog-Jumping Contest," in which Donald and his nephews take their $3,000 prize to an expensive restaurant to buy the most expensive dish is pretty great. I love the fact that here Donald has so much cash that he's not only stuffed himself with it like a scarecrow, but the serene expression on his face, as having a sailor's hat bursting with bills is perfectly natural (Louie, by contrast, cracks a smile).
But I think
this panel from the title story, in which Donald and the boys drive past Gladstone in their new, absurdly impractical-looking car, purchased with the $2 million that Uncle Scrooge gave them for saving the life of his unicorn, is the best ostentatious demonstration of wealth. It's not just the ridiculous luxury car itself—the fact that appears to get TV and/or radio in 1949, the monogrammed car door, the hood ornament bigger than the kids—or the fact that they've hired a driver in an elaborate uniform.
It's the fact that they've hired a second guy in an elaborate uniform to sit next to driver, apparently for the specific purpose of insulting other drivers with less ostentatious cars.
