Needless to say, I'm fairly annoyed with this deal as I just bought it from Amazon Marketplace for £8.50...
CD-Wow have the 4-Disc "Ultimate Edition" of the Back to the Future Trilogy for £7.20 with free postage. It's a STEELBOOK edition, which means that it comes in a really cool (and very collectible) metal case. And there's a heck of a lot of special features too!! The next best price for the steelbook version of this boxset is £12.98 delivered at Amazon.
Also remember that if you've signed-up to the CD-WOW mailing list, you've probably got access to a voucher code or two that you might be able to use: they seem to send them through every few days.
Features BACK TO THE FUTURE in which a Californian teenager becomes the innocent victim of a local crack-pot's invention - a time machine made from a DeLorean car. He finds himself in his home town thirty years back where he is in for some embarrassingly funny surprises. In BACK TO THE FUTURE - PART 2, a visit by Marty and the Doc to the year 2015 seems to resolve a few problems with the future McFly family. When they return home, they discover someone has tampered with time and Hill Valley, 1985. They must once again get back to 1955 to save the future. In BACK TO THE FUTURE - PART 3, Marty is stranded in 1955 and must now travel to 1855 to rescue Doc Brown. Surviving Indian attacks and unfriendly townsfolk it's up to Marty to grab the love-struck Doc, leave the Wild West and get back to the future.