I recall some free mortgage website templates some time back. Perhaps it was those from Pilot Group because that is all I find this morning.
The reason you probably can't find a good/free mortgage website is due to the labor that goes into developing the mortgage website content. Remeber that if you want your site to be productive in the search engines you will need quality content (content is king).
Of course the cheapest solution would be to find/purchase a general template (some available here:
http://freesitetemplates.com/)and then develop the mortgage content yourself, however when you find the mass of hours required to develop something worth while, I think you may agree that your time is more cost effectivley spent closing loans.
Plus don't forget that the start up phase, which could easily last a year, would be a learning experience were you find out one by one the things that don't work as planned.
Best of luck,
John