I use to play for lower teams, mainly MSK Zilina (Slovak 1st league), so I can't really buy and sell too expensively, but... One season I bought Gabriel Torje for 2 million â‚¬ (had the money from previous very succesfull season) in summer. A few months later I sold him for 4 million â‚¬ to LiÃ©ge I think. Now that's business. Double the money in less than 6 months!
Boughts from Genk - Â£22 thousand.
Sold to Portsmouth - Â£3.5million