If you were spoofing GPS campus wide over 1.544 GHz and had all your GPS sentences correct, with simple radios and antennas... and you hadn't got in trouble with Uncle Charlie or the FAA....
Still, it was illegal and could get everyone expelled, so I wouldn't do it again.
Broadcasting an RF signal to spoof GPS (and especially across a campus), that my friend, is not trivial or cheap.
But broadcasting a loud signal that tells everyone in range that they are at the same exact point doesn't seem too hard to me. Couldn't that even be as simple as replaying a single-antenna recording taken somewhere else?
Doesn't work well with some receivers that cache data from the real network and stay locked onto the much weaker real signal. But works with most receivers.
From your previous comment, it sounds like your experience may have been from a while ago? In 2022, it is fairly trivial and cheap: https://github.com/osqzss/gps-sdr-sim
I can not ;^) personally confirm that this works with a HackRF, which is like $300, but probably also with any other reasonable tx-capable sdr.