Humble Daisy is currently offering the software for 75% off its retail price from today until January 24 to celebrate the Mac's 25th birthday. ProfCast normally retails for $59.95USD, and education discounts are available, but the sale brings the price down to $14.99. ProfCast requires OS X 10.4 and later.
And for the confused, myself included, ProfCast's Web site does say that the discount is for 25% off rather than 75%. However, by clicking on the coupon for a single-seat license, you can see that the price really is $14.99.