Over here in Northern Ireland I use
www.propertypal.com which allows me to search my areas drawing round them on a map allowing me to determine -
When some of my houses go on sale and are agreed/sold.
What other houses in the areas I work are up for sale.
What houses in my areas have sold in the last year.
What houses have just been let in the last year.
The information is well set out and once I have my search criteria I list it by house value and use this information for future specific house targeting and canvassing high value work in areas I already work.
For example I might see a house sold local to where I currently have work for 400k and by viewing the pictures on the site I can price the work and every time I am in the area I call until I get a response.
I have a list of about 50 houses selected this way which I target whenever I can and though it may not sound like a lot I picked up £70 of new monthly work close to my own work since Christmas.
Not sure if yous have a similar site for the mainland but it could be worth looking at.