Scottish Highland Property Services is a small estate agents focused on highland properties:

http://www.scottishhighland.com/

The website can be a little confusing when it comes to property search - don't make the mistake of clicking on "Browse all properties", as there's no real order to the listings - use the "Search all properties" link instead to narrow the listings down nearer to your critieria.

There are some nice properties on there, most of which are displayed at Your Move.