As the title says, toolstation have a good quality alarm bell box dummy for sale in their clearance section.
A good cheap visual deterrent against potential intruders, We have one at the front and back of our house. Good quality and easy to fit.
Cheapest authentic looking dummy box I can find by some margin.
Buy 2 and then something cheap to get the order over £10 to quality for next day free delivery (otherwise £5).http://www.toolstation.com/shop/Clearance/Security/Bell+Box+Dummy/d50/sd2599/p30493
Hope this helps someone
The real bell box (with internal alarm) is also on sale at £16.25.