There are several ways to do this without paying too much, if anything at all. Some of my suggestions would be to:
1) Start a blog - you can download a wordpress template and use it as your own website. The search engines love wordpress blogs and if you write about your local area, eventually you will come up on the first page of results for local searches. Eg. Write about "Property values in Austin Texas" and soon your site will appear on the first page of results for that particular search string. This is how you target your audience. It doesn't require much programming knowledge to use a WordPress blog and only a few posts a week will do wonders.
2) Use a syndication service for your listings - There are several websites that will take your listings and feed them out to all the popular real estate aggregators (sites like Trulia). Brokerfeeds.com is one of them. I am the Sales and Marketing director for Brokerfeeds.com so I know that it is a free service for individual agents with a few listings and we publish to over 25 different sites. Most of those sites will link back to your own website, which will help your page rank significantly.
3) Post articles on popular real estate sites - If you write articles about timely real estate issues and become an expert to readers, you will find that you have more business than you know what to do with. I know realtors that write about their local market, post market analytics, answer questions and target a specific audience. Pretty soon, the phone will start ringing. As home buyers and sellers search the internet, they will come across your articles and if link back to your own site...even better. Do a google search for "real estate blogs" and you will find plenty to write for. Active Rain is a very popular one.
Might have told you stuff you already know, but I hope this helps! I'd be happy to answer any other questions you have.