I agree with the above that you'd be spending a lot of time trying to protect what is effectively public information.... however, if it's very important to you there is an option open to you.

You can serve up different content based on the IP addresses of your competitors. Not cloacking, just dummy data to a few competitors.

All you need do is get the IP's. To do this, I suggest emailing your competitors (probably on you email lists?) with something too enticing to not click on and then keep a log of those IPs.

The above isn't full proof but does add an extra hurdle.

__________________
@seopo | Estate Agent Website Design | Property Social Network