I got to school at CSU currently, so I can help you out! So, many of the lower cost apartments aimed at students are full by February or so, on a technical/superficial basis. But, there are so many options. It's quite easy to find a place to live - either taking over someone's lease, or by subletting, or by people looking for a third person to rent with! Lots of students study abroad, have plans change, etc. Decent apartments (price wise): Ram's Village (I've lived there), The Lofts (live here... very thing walls), Ram's Pointe.
Here is a great CSU website that I (and many people) use often:
http://www.rentalsearch.colostate.edu
You need to be a CSU student to use it (not sure at what point you can use it? might be after you apply, might be after you are accepted), and you can post yourself as a person in need of a room, and peruse the available rooms. If you can't access it, try signing up as a landlord. ;P Or, I can search on there for you! I don't mind helping out.