I did this bid last semester to convince students to take my AP Economics class and it worked perfectly. Sadly my class got canceled for budgetary reasons (the economics of economics?), but this video shows how an all-pay auction would be a good sell AP Political Science too:
Via Marginal Revolution. This is how the online auction site Swoopo.com works. They sell a flat screen TV for $12, but make hundreds on sale. Find a product and watch the bidders countdown, as long as you're the one watching, not bidding.