Each sheet of 20 is going to cost $19.99. The amount over and beyond the cost of a regular book of 20 stamps must be the portion donated to Idol Gives Back. It looks like the Kelly Clarkson ones are being sold as 42 cent stamps. Maybe they figure by the time they get them mailed out to the consumer it will be May?
Cool. I finally get to "lick" Taylor!
OMG!!! I've dying to use this line!!! 
Kelly Clarkson stamps are now available; each 20-stamp sheet has four images of the first Idol. The next five Idols — Ruben Studdard, Fantasia, Carrie Underwood, Taylor Hicks and Jordin Sparks — will be released on the next five Tuesdays. Another set will come out when a new Idol is named in May.
That would be May 6th...
(thanks to cochem on boogie for doing the math)
Do you suppose Taylor even knows this is being done?