This seems like a great potential offer to me, simply purchase one of the Pre-order Harry potter books for half price and then Amazon will automatically give you over £150 discounts on selected Books, CDs, Video Games, Toys and Electronics & more.
Remember that if you order through http://www.cashback-rewards.co.uk
you'll receive 4.5% of any Amazon purchases and a free £5 welcome bonus (similar to Quidco) and the discounts include:
£1 off selected Books | £1 off selected CDs | £5 off selected Video Games | £30 off Digital Picture Frame | £24 off DVD Burner | £1 off selected Toys | £1.50 off selected Toys | £2 off selected Toys | £3 off selected Toys | £5 off selected Toy | £7 off selected Toy | £25 off selected Toy | £5 off selected Baby Products | £10 off selected Baby Product
I hope this helps anyone looking for decent discounts on Amazon and this is even better for anyone that likes Harry Potter books. :)