Lightrail
See http://www.rtd-denver.com/lightRail_subHome.shtml
For lightrail, the standard cost for one-way fare is $2.00, but they do have discounts for seniors, students, etc. See this chart for more info: http://www.rtd-denver.com/LightRailFares.shtml. One can take the E, F or the H line to the University of Denver Station.
Getting from DIA to someplace else
Getting from the Denver International Airport (DIA) to the University (or nearby hotels) is another matter.
For a bus, you could take the RTD SkyRide to the Nine-Mile station (The "AT" bus at about $8-10), then take the lightrail up to the Colorado Ave station where the La Quinta and the Fairfield Inn is. If you have a hotel downtown, the "AF" bus goes downtown to the Market Street Station. See:
http://www.rtd-denver.com/skyRideFares.shtml
http://www.rtd-denver.com/HowToRideSkyRide.shtml
http://www.rtd-denver.com/PDF_Files/skyRideMap.pdf
You could also take a cab to the University or your hotel, but it might be well over $50.
One could also rent a car from DIA.
One could take Super Shuttle from DIA to your destination.
Here is some info on parking at DU -- Look at the bottom of the page.