There are many free solutions just as explained above (like the open realty) but many of them lack one important feature: SEO.
Also, most of you (or us???), real estate pros, do not have the technical knowledge to work with scripts, change things here and there on the scripting, find a good hosting or even that above mentioned SEO. The website of a real estate agent should have one important goal: to generate leads and contacts for the agent and most of the times the website itself is not enough. You need a lot more than that. This is why we built Mondinion.com and we will soon come up with a great offer for you, real estate agents. Stay tuned, we will announce this soon here.