#10 David Grondin

Grondin joined Arsenal in 1998 from St Etienne for a fee of £500,000. Much was expected from the French left-back but after a shaky start to his Arsenal career, Grondin was loaned out to various clubs.
His series of loans spells started at St Etienne in 1999-2000, Cannes in 2000-2001, and then to Beveren in 2001-2002. In 2003 he joined Scottish side Dunfermline Athletic on loan initially, eventually signing a permanent deal until the summer of 2004, thus ending his forgetful spell at Arsenal.
Grondin made 4 appearances in total for the Gunners and another cheap bargain that flopped big time.
Arsene Wenger might have made mistakes in the transfer market but it is small change compared to what Manchester City and PSG spend on a single player.
If all Premier League clubs are given £100 million to spend, it would be interesting to see who comes out on top - Guardiola's Manchester City or Wenger's Arsenal.