This is the cheapest i could find the original triolgy blurays online as a preorder. to get the cheapest price make sure you:
1. Use the HMV code: MOFFHMVO5 to get £5 off over a £30 spend
2. Use quidco/Topcashback for 1% (28p) cashback via a sale using a voucher.
Hope this helps someone :)