I lived in the dorms my first year (the only year it's available -- you can't live in dorms as a D2 or beyond) and I thought it was a good experience. The price is comparable to what you might see elsewhere for something so close to school (I lived in Stuyvesant town -- HUGE apartment for New York less than 10 minute walk from school). The big advantage of doing it this way is so you dont have to search around while you're not here. Finding an apartment in New York was a horrible experience and I couldn't imagine having to do it without ever having been here to know the neighborhoods or to walk around and see a place during the 1-3 days it would remain available.
Also, keep in mind that pretty much anywhere you try to rent is going to ask for a guarantor making around 70 times the monthly rent. So on a $2000/mo apartment, that's $140,000. If you have someone you know making that much willing to sign for you, awesome. If not, give up on the idea of renting and go to craigslist looking for shares.
If you want a complex, there are nice apartments at Stuyvesant Town/Peter Cooper Village, Waterside Plaza, and Kips Bay. All elevator buildings close to school run by big management companies (so if you get locked out at 1am you can call someone to let you in -- not true with most landlords). You might save money searching around for something else though -- try craigslist or
http://www.urbansherpany.com/ for no-fee options. You'd also save money by trying to commute out of Queens or Jersey, but again, I wouldn't want to rent without knowing the neighborhood...
Hope that helps some.