In fact, economists show that government backed loans have driven up tuition prices[1]
[1] http://www.nber.org/chapters/c13711.pdf
"As column 4 demonstrates, the demand shocks- which consist mostly of changes in nancial aid-account for the lion's share of the higher tuition. Specifically, with demand shocks alone, equilibrium tuition rises by 102%, almost fully matching the 106% from the benchmark. By contrast, with all factors present except the demand shocks (column 7), net tuition only rises by 16%."