If you can crack this, it will be a very lucrative opportunity but I am afraid that the space is too crowded and there is not enough of a value proposition for quality candidates to give you their updated info.

Also doesn't Linkedin already do this. They have a search engine you can use to filter out applicants based on school, past experience and location. I also believe they released a lite version to make it more affordable.

Some startups you should look at if you're interested in this space: Hired.com, Whitetruffle and Wayup.com (they introduced a way for companies to post requirements and get paid per qualifed applicant)