Are you thinking of having your school’s computer department write the software?
It sounds like a great idea, but schools that do that get very mixed results. Here are a few articles we found that shows the horror stories of failed student elections. Do you think saving a couple of dollars was worth it to them?

“Online voting for Barnard's Student Government Association was suspended on Thursday owing to technical difficulties…Shetty added that the only problem with the online system is that an external office--Management Information--must manage the elections for SGA.”
-- Columbia University, http://www.columbiaspectator.com/vnews/display.v/ART/2003/04/11/3e9676f67e74

“SGA faces several difficulties every year with the different online vendors… SGA officials potentially go through a new vendor yearly and essentially, Conrad said, have to start over at ground zero….Conrad said this is because the state-regulated bidding process which requires SGA constantly to chase the lowest bid…This process can create problems when desirable qualities of a vendor supercede cost…Walker said inconsistencies with different vendors have plagued elections committees from an administrative aspect.”
-- Kansas State, http://www.kstatecollegian.com/stories/030502/new_balot.shtml