Running peltiers (electrical) in series is possible.
I've got two 24V @ 15A PSU's for $35 a piece at E-bay. Very cheap, at least for people living in the USA.
I don't have them yet, but Phreenet send them to me a week ago, so they could arrive any day now

. (I'm living in the Netherlans, and he was kind enough to help me getting those to me)