With the January transfer window now upon us, Premier League clubs will be making plans for a signing that could make a difference come the second half of the season - whether they are fighting for Europe or trying to avoid relegation.
Here's a look back at some of the better value signings made in a window known for being notoriously hard to operate in.
5. Gary Cahill (Bolton to Chelsea, 2012)
Chelsea signed centre back Gary Cahill from Bolton for £7m back in January 2012, and it's fair to say that he has repaid that transfer fee with his performances. In an inflated market like today's, it's incredible value for money.
Cahill's honours since joining the Blues include; two Premier League titles (2015 and 2017), an FA Cup (2012), a League Cup (2015), a Europa League (2013) and a Champions League title (2012).
4. Clint Dempsey (New England Revolution to Fulham, 2007)
Fulham paid £2.7m to secure the services of Clint Dempsey from New England Revolution in January 2007.
He made 225 appearances for the Cottagers between 2008 and 2012, scoring 60 goals. The United States international was also part of the Fulham team to reach the Europa League final in 2010.
He was sold to Tottenham Hotspur for £6.75m in the summer of 2012.
3. Nemanja Vidic (Spartak Moscow to Manchester United, 2006)
Vidic played exactly 300 times for Manchester United after signing from Spartak Moscow for £7m in January 2006.
The Serbian was a stalwart in a Manchester United team who ended up winning five Premier League titles (2007, 2008, 2009, 2011, 2013), three League Cups (2006, 2009, 2010) and a Champions League (2008).
He left United in the summer of 2014 before retiring eighteen months later.
2. Luis Suarez (Ajax to Liverpool, 2011)
Luis Suarez is most expensive signing on the list, but possibly the one that made the biggest impact on his club.
Suarez signed for Liverpool from Ajax in January 2011 for a fee in the region of £22.5m. He went on to score 82 goals in 133 appearances for the Reds, most notably hitting 31 goals in 33 Premier League appearances in the 2013/2014 season.
His goals lead to Liverpool fighting Manchester City for the title, missing out by only two points after a late season collapse. His form that season led to him being voted as PFA Players' Player of the Year, and to Barcelona purchasing the forward for £64.98m that summer.
He's been a rousing success in Catalunya, too.
1. Riyad Mahrez (Le Havre to Leicester, 2014)
Leicester signed Riyad Mahrez from French club Le Havre in January 2014 for £400,000.
At the time, the Foxes were riding high in the Championship. He scored three goals during the second half of the season as Leicester were promoted the the Premier League as champions.
After playing an integral part in the 'Great Escape' season of 2014/2015, Mahrez was named PFA player of the Year in the next season as Leicester shocked the world by becoming Premier League champions. Mahrez scored 17 goals and provided 11 assists for the foxes that season.
Speculation now is that if Leicester were to sell, they would demand at least £50m for the Algerian. It's fair to say that £400,000 was a good investment.