From the NCES:
For the 2011-12 academic year, the average cost of attendance and the net price of attendance varied by institutional sector. Among full-time, first time degree/certificate-seeking undergraduate students receiving any grant aid, the average cost, for those attending public 4-year institutions, was approximately $18,300 and net price was about $11,700; for those attending nonprofit 4-year institutions, average cost was roughly $35,200 and net price was about $20,600; and for those attending for-profit 4-year institutions, average cost was approximately $27,000 and net price was about $21,900. This provisional First Look report includes fully edited and imputed data from the Integrated Postsecondary Education Data System (IPEDS) winter 2011-12 data collection, which includes the Student Financial Aid component data for the 2011-12 academic year.
The full text report is available here (PDF) or embedded below.
This provisional First Look presents fully edited and imputed data findings on student financial aid, including the number of undergraduate students receiving aid and the amount of aid received by those students for the 2011-12 academic year.