I was looking at upgrading my 2Gb iMac memory but i'm not sure about who i should buy it from. The official Apple store 4Gb memory is £198 compared to all the other sites i looked at which range from £30 to £60. This is a ridiculous price difference. The problem is these sites have nothing to do with Apple and there is no garentee that the memory will work. www.crucial.com was the main site i looked at and seemed legitimate enough.I was wondering 2 things. 1. Why is the apple memory so much more expensive, is it just a massive markup or is it faster/higher quality? 2. has anyone used these sites, do you think there ok?