a current student here
ESF is fairly cheap by most standards - you get an education you could get from a bigger college for a state college price, as well as access to everything at SU, if you so please. However, if you have a broad range of interests and aren't just narrowly focused on the environment, that access to SU seems almost essential. You won't really find anything other than that on the ESF campus.
Centennial is insanely nice, but the price is huge (somewhere around the 6th highest room and board in the nation, I think). If I wasn't getting most of the money from financial aid, I wouldn't be able to afford living here. And getting an off-campus apartment with a few friends is definitely cheaper once your second year comes up (as well as having all of the other associated advantages).