The post above gave you the interests of most common loans - Stafford and Perkins. However, there is a catch. These loans are only offered to qualified students and there are annual limits.
You mentioned $20-30W. That means you plan to borrow full prices for a private college. I don't think Stafford and Perkins will cover that much. You will have to get plus loans and other private loans with higher interests.
This is the first time I have even seen anyone who will borrow the whole amount. I don't think any university worths that much debt.
What is your situation. May be you should first try to understand the FA system first.
