6. Andrey Arshavin
Bought for: £16.9m by Arsenal in 2009
Sold for: Free to Zenit St Petersburg in 2013
Arsenal manager Arsene Wenger went in search of some Eastern European genius with the Gunners' season flagging in 2009, parting with a club record £16.9 for diminutive Russian forward Andrey Arshavin after watching him dazzle at the European Championships a year prior.
Arshavin started life at the Emirates in a rich vein of form but ultimately failed to deliver consistently, despite scoring four goals at Anfield in a single game during a breathless first year in the Premier League.
Rather sadly Arshavin's time in North London ended with a whimper last summer, returning to Zenit St Petersburg on a free after spending part of the previous campaign back on loan at his former club.