there is a fairly cheap hotel near the airport. it's a few blocks off the strip, between the MGM and Luxor.
http://www.lvtravelodge.com/
just checked their calendar, and they are sold out beginning the 12th...you guys must have picked a busy week.
edit: the place you're staying shouldn't be too bad, provided you are traveling north to LV. but you should know that there is little else at that exit.