Most campuses don't have video cameras watching random streets in front of the building. Hell, most campuses don't even have cameras in the buildings. A few of the buildings at my campus just got upgraded recently because there were some laptop thefts. Most buildings still don't have cameras.
You totally could have gotten away with it. The campus would likely report a missing monitor to Dell, who would mail out a new one under the assumption of a shipping error. The campus has a contract with Dell requiring them to take responsibility for shipping errors. If they ordered that many monitors, then I guarantee that they have such a contract. I did campus IT for awhile, the university essentially loses no money in case of theft or accidental destruction of computer hardware.
I wouldn't have done it either though, the fear of getting caught and the conscience nagging you would do it.