If you are determined to stick with Michelins then you are going to nhave to pay the price, but there are loads of equaly good tyres around for half the price. ATS and Kwik fit are a rip off and rely on folks who dont want to shop around and can aford there prices. Also, they know nothing about fitting tyres to high performance cars. Check out www.blackcircles.com, or, www.mytyres.com, they deliver to your door and you can arrange fitting your self or choose form their appointed fitters and do it all on line.
Much much cheaper, I saved £150 with my last set of Conti Contact Sport 3's, which are also fitted as standard equipment.