I heard from a posek that ALL monies spent at a Chinese auction is considered maaser except for the amount spent on the winning ticket.
The question is when Chinese auctions become too over-the-top, too gashmius-oriented. A dancing dollar bill is very cute, but it’s the wrong message. Organizations bringing ruchnius to the frei and preaching “gashmius is worthless” shouldn’t turn around to the frum and give them the same gashmius they tell the frei to ignore. It’s hypocritical. At least it’s more honest than the “donate to us and you’ll get all the yeshuos you could ever need” approach.
I know someone who made a fortune in the tech bubble, only to lose all of it. He was very makpid on giving maaser kesafim. He still is proud of giving 100k maaser, but as that was the only money he ever took off the table, he has nothing to show for it. As many will tell you, the bracha of riches by giving maaser only applies to maaser dagan, ie maasser required from the Torah, not to mitzvos derabbanan like maaser kesafim.