2. Ashley Cole ( £5,000,000 + William Gallas )
When Chelsea signed Cole from Arsenal under acrimonious circumstances, they did it for a remarkably low price. The 5 million pounds and swap of William Gallas, a player threatening to score own goals if he wasn't sold, turned out to be a win-win for Chelsea as in Cole, they had signed the best left back in the Premier League.
Cole quickly established himself as undroppable and won everything during his time at Chelsea. He won the league with Carlo Ancelotti at the helm, a League Cup, 4 FA cups in addition to the 3 he won at Arsenal, for an incredible 7 FA Cup winners medals. He also won both European trophies in back to back seasons, establishing himself as one of the best left-backs in world football.
His legacy, as a player anyway, is incredible. He won the England Player of the Year award in 2010, twice winning the Chelsea Player's Player of the Year Award and making the best ever Premier League team, as chosen by panels and pundits after 20 seasons. Ashley Cole was an absolute bargain.