WTF is going on with the price of that?? I purchased a 105 5800 groupset over 3 years ago for £299. And yes I'm sure, I've just checked my old order on Wiggle... does the price for these really not drop over time as they are not brand new anymore?
There was a weird glut around a year after release when shimano sets were really cheap, then they popped up. IIRC 105 went up to ~£500. I got a unused Ultegra set for £300 and Hydro groupset -cranks for £300 also. Was amazing at the time, evven more-so now
Shimano 105 5800 Groupset is £299 and more black friday deals
http://www.wiggle.co.uk/shimano-105-5800-groupset/