Here's the trick to avoid paying those tickets, especially if you don't go off campus too often:
Don't register your car, and park on PA Ave. I haven't seen anyone suspicious (other than people I know) in the few blocks either direction from the campus houses, and as long as you park early on street-cleaning days, you can usually find a space pretty close to the apartments. Only park on campus when you have to (I recommend the visitor lot by Campus Safety), and do your best to move your car as soon as you can. I got one ticket last year with that strategy, and just didn't park on campus any more. No losing money, no hassle.
Of course, your car is already registered, so that tactic might be hard to pull off (though they had my liscense plate number from the year before). I'm not sure if they actually do anything to you for not paying them, anyway. Personally, I wouldn't worry about it until someone calls your voicemail or puts something in your mailbox that says you need to pay it...
Of course, I'm lazy and easily annoyed by faux authority, so what I'd do might not be the best move.