Some internet providers give access to ESPN3 even without a cable tv subscription.
If you know someone who will share their cable TV subscription's email and password, you can use that to get access to ESPN3.
If those two suggestions don't work for you, then Sling is probably the next cheapest option to access ESPN3.
Only time ESPN3 doesn't carry the live stream is when the games are carried on ESPN's other channels which happens normally in the playoffs. In those cases you can still stream the games using the WatchESPN app but you'll need access to those ESPN channels and not just ESPN3 so you'll need either a Cable TV subscription login or Sling.
Thanks everyone for your help on this. I'm moving to Louisville, KY, so I'll be looking for a tailgate at ISU-b! One last question, are the home games on WatchESPN too?