Hiya, we got one when there was an offer on in Tesco, we paid £50 for it which I thought was pretty good! I read some reviews saying it didn't work if the baby had moved around the cot, but turns out you have to put a bit of ply board on top of it the full size of the mattress (under the mattress of course) so that it picks up bubs movements wherever he or she is. Of course you can use it without the sensor mat too if it's causing too much stress. Oh I've not had a chance to use it by the way, just read loads!!