If you are able to convince yourself you will get 'peace of mind' at £200, I genuinely, and this is no joke, would not actually bother
with any of the rubbish you'll get at that price point and spend £10 on a dummy bellbox.
It will be just as effective at stopping a determined intruder as it is at warding off a casual one.
But better yet it will never false alarm, never require servicing, batteries, or the hastle of telling friends and neighbours
how to operate it.