Just found this after searching around for what most of my friends have said is a must have monitor.
The price at the moment is £69.99 but using the following voucher code AFPE22 brings the price down to £62.99 with free delivery or collection in store.
Quidco is available at 3.5% for new customers and 1% for returning customers.
Also, if you are part of the Baby Club you get 10 Advantage Card points to every £1.
This is the cheapest I have been able to find.