Interesting to know...
Is Christie's like eBay where you only pay some amount over the runner-up's top bid, or is it just an ordinary auction where you pay the price you bid?
Yes, it is like eBay, at least for online auctions:
"A max bid sets the highest bid you are willing to place on a lot and continues to bid on your behalf until that bid is exceeded. If two or more bidders leave identical bids, the first bid received takes precedence. You can change your maximum bid amount if the current bid is lower than your maximum bid."
