I'm Gretchen Hirsch, class of '60, and I'm a writer, too. I'm also a book doctor, which puts me in touch with agents occasionally and I've met many over the years by attending writers' conferences. Four of my books have been agented. Two were not, and the process went OK without one, but I prefer having one. My current one is very good (but I don't give her name out unless I know the author and the book).
Is your book fiction or nonfiction? That makes a difference in how you approach an agent.
If you are local, I'd suggest that you attend the Columbus Writers Conference in August. You can find out all about it at www.creativevista.com. I'll be moderating two panels, and the sessions look very interesting this year, as always. There are always agents there, as well as editors, and you can find out a lot about the process.
You can reach me through e-mail. I'll be glad to share information.