They should probably include the information as a link in the FAQ, as it's currently "hidden" at the bottom of the "APPI ONLINE" page located here:
http://www.appic.org/match/5_3_match_application.html
$35 for the first application, $10 for each additional application up to a total of 15, $25 each for application numbers 16 through 20, $35 each for application numbers 21 through 25, and $50 each for application numbers 25 and above.
Last year, the initial pricing structure was similar (i.e., $35 for the first app, $10 for each additional app up to 15). After that, it was $25 per app for any number of apps over 15, I believe; I submitted 17, so if it changed above 20 I don't know, but I don't believe that was the case.
Honestly, I approve of the progressive price hike, as it will hopefully prevent applicants from overdoing things a bit and applying to 30 or 35 sites (which, based on what I heard during interviews last year, wasn't uncommon).