Spotted this Hot Wheels MEGA PACK at Asda Newport.
was £60 down to £25 and then only £12. I thought it was overpriced (as all these retailers does or give impression of sale). checked at Amazon and just only tower pack is at £59.69 (link: http://www.amazon.co.uk/Mattel-BGX86-Wheels-Track-Builder/dp/B00FAQVY5E)
this pack contains towser set + Alien launcher + Crate Crash + 5 Cars.
not sure if it is nationwide but worth checking your local store.