Besides the obvious word of mouth (not particularly helpful if you don't know a slew of people) there are time tested, proven methods of selling a book (or at least getting the word out there) that don't cost a lot of money.

First, create flyers and post them around college campuses, coffee shops, hair salons, boutiques, etc.

Next, place small ads in neighborhood and college newspapers. They only need to run for a day or two at the right time, like during the holidays or homecoming. Placing the ad for a limited time keeps costs down.

Also, utilize independent booksellers in your area. They can be a great resource and support system when it comes time to schedule book signings and the like. They, of course, will also carry and sell your book.