Why does it have to be a 3rd party lender? Have you filled out your fafsa and spoke with your financial aid dept at the school? Also have you tried to fill out for scholarships as well? A couple good sites for scholarships are www.fastweb.com
You should fill out a profile on both of those sites and then apply for as many scholarships as possible, also make sure to fill out the profile things as COMPLETE as possible because any free money is better than taking out loans. Even 500 bucks that you dont have to pay back is better than paying it all.
If you have exhausted all other options and legitimately need a 3rd party lender I would just go to every bank and credit union in your area and get all the details and compare and contrast them, then go to online sources of other banks or credit unions that may not be in your area and check their deals too. Most of the ones you will find will basically be the same or pretty darn close in options and interest but I honestly think that you should be fine with federal because they tend to be a tad bit lower interest than most other loans you will find from 3rd party lenders.