I don't think you will be able to find what you are looking for. Contribute editability requires that Dreamweaver proprietary code be inserted in the page(s). The only way you would get that would be to code it yourself. But most of the information you are talking about editing is not actually on the page itself, it is pulled from a database. There are a number of 'open source' type programs for things like this - OpenRealty is one that springs to mind, but there is no Contribute editability there. On the other hand, it comes with a robust back end for administering the site so there may be no need for Contribute at all....
Take a look at WordPress.org. Requires PHP/MySql 5+.
Your client can update content anytime/anywhere from their web browser by logging into the admin area.
Real Estate Themes for WordPress
Real Estate Plug-ins for WordPress