I'd be happy to conduct robocall advertising the event among whatever demographic and in whatever geographical area you want based on the Iowa voter database. All I'd need is a wave file and I could give you a cost estimate based on the message length. Just frame the message as non-commercial so telemarketing rules do not apply.
For anyone considering robocalls in the future, I highly recommend Dynamic Interactive. The owner is a Ron Paul supporter [deleted by rp08orbust]. They bill in tenths of a second. So a 30-second message would cost at most $0.0125 per number dialed (probably a lot less, because you are not charged for non-answers and the robocalls hang up on answering machines).