Here are the verbatim details from Comic-Con International:
They will be selling returned single day badges through EPIC online registration. An adult single day badge will be sold at the rate of $40 and Junior, Senior, and Military single day badges will be sold at the rate of $21 each. Sunday adult badges will be $23, and Junior, Senior, and Military Sunday badges will be sold at the rate of $13 each. These prices include a $3 reprocessing fee.
At this time, unfortunately, we are not able to accept Discover cards for Comic-Con badge registration.
You may purchase up to TWO single day badges only!
Go here for details.