StackSocial offers The Name Your Own Price WordPress 15-Theme Bundle for whatever you want to pay. The minimum price is $1.01, which buys you only three of the themes; however, if you opt to pay the average (at the time of this posting it's $7.67), you'll receive all 15 themes. Assuming you pay the average, that's $817 off and the best price we could find. Note that 10% of your contribution will be donated to your choice of charity. (Choose from Child's Play, World Wildlife Fund, or Creative Commons.)
Before you send in your tax return, double-check that you haven't made one of these mistakes that can trigger IRS scrutiny.