It totally and completly depends upon geography. The biggest expense you will have is rent. And it is next to impossible to say what you can get for your money without knowing the standard of living in your town/city.
For instance, I went to college in the oldest city in Iowa, that had a population of 60,000. 3 friends and myself rented out an entire victorian house (3 story, with garage) for $595 a month. So we paid like $150 a person plus utilties.
Now, I moved down to a different part of Iowa, which is also about 10 minutes away from the University of Iowa. Now, my girlfriend and I pay $610 a month for a condo that has about 1/4 of the living space that our old house has.
And, the water bill that 4 of us paid was lower than what the two of us pay now.
So, your best bet is to find a local paper and start looking through the "for rent" adds to see what places are going for.
Your cheapest places will be "efficiencies". Avoid them like the plauge. An efficiency is basically - 1 corner of the room is your bedroom, another corner is the living room, the third corner is the kitchen, and the closet in the fourth corner doubles as the bathroom. Beleive me, you would almost rather live in the doorms than in one of these.
Also, take into consideration off street parking, and how much they will charge you for it. See what utilities are included in your monthly rent (Electricity, water, gas, heat, ect), see if they have onsite laundry. Check to see how secure the place is. Look and see how many outlets each room has. Don't be afraid to ask the landlord to clean it before you take possession. If they don't clean it, then ask for a reduction in your first months rent. If they refuse to do that, then you don't want to be living in their building.
I'll break down all the major monthly costs that you'll have to take into consideration(with my current prices in parens)
1) rent (610)
2) gas (25)
3) electricity (70)
4) water (40)
5) telephone (60)
6) parking(maybe) (free)
7) garbage (included)
8) food (300 for two of us)
10) car insurance(if you don't pay for that on your own already) (1600 year for two drivers and two cars)
11) entertainment (200 or so)
12) cable (don't get it, but figure $45)
13) internet access (free for me, but figure $30)
Don't forget that moving into a place itself is expensive too. You have to get furnature and appliances, provided you don't get any hand-me-downs. You also have furnish the place - blinds, drapes, curtains, ect.
All in all, it isn't cheap, but it is rewarding, and it beats having to abide to the mickey mouse rules that colleges impose on you
