Oh man, I totally feel you on the whole "buying for a university department" thing and trying to squeeze the money. But let me tell you. Anything less than that Tornado Coin-Op is really not going to cut it. I go to a school where there must be 10 tables on campus (within the dormitories, etc.) and my campus organization has the nicest table in the school. But still, it's in really really really annoying condition. It's a Tornado Cyclone II, and just through my organization playing it for only 2 years (after being played for an unknown amount of time, we bought it used), the playfield is warped (it can never be level), the pins in the men are loose (makes bouncing less "live"), the bearings are shot (I think someone used WD40), and the rods are terrifically bent.
Now I'm not saying that these things could have been fixed if it was a coin-op. But the rods probably would have lasted longer if it was the coin-op, if you take care of it well, you won't run into the problem of the bearings, the pins is a usual problem and only requires small maintenance, and I don't even know how the playfield got so messed up.
Anyway, get the coin-op. it'll serve you well.