I've updated the All Time Record Comic Book Sales page with a nice little chart illustrating sales over the past 20 years. It's new, so let me know if you experience any issues. It should work in the latest Chrome, Firefox, Safari, Opera and IE9+.
Here's a snapshot of the chart. It's not interactive. The real one is.
The chart is interesting in that it shows two separate events that changed the playing field over night. The introduction of CGC in the early 2000s (since
I have incomplete data on those early sales, they actually stack up right at the beginning of 2000) and then the series of record sales in 2010, which immediately changed the range. We used to have a solid ceiling of $350,000. Overnight we went to world where multiple sales in individual auctions would break that barrier.