In the early 2000s, Barcelona paid a record transfer fee 19.5 mil to secure the services of Ronaldo (Brazillian). This record was left dead in the water by Real Madrid's 50 mil deal for Zidane and Buffon's 53 mil transfer to Juventus. It was also around this time that people were shocked at Man Utd's 30 mil fee for Ferdinand. Back then, 20 mil was a soft cap and only mega-rich (or successful) clubs can have players over this limit (just for the sake of comparison, Liverpool's record transfer in 2004 was 14 mil for Djilbril Cisse, the Ligue 1 top scorer). Of course, mega rich clubs can ignore this as evidenced when Real Madrid bought Beckham for 35 mil and Barcelona got Ronaldinho for 30 mil. It was around this time that Roman Abramovich came to Chelsea, which allows them to secure 5 players with transfers worth over 10 mil, which also includes 24 mil for Didier Drogba (again, for comparison, Harry Kewell, an established player in the Premier League, only cost 5 mil). The next season, this trend continues with Chelsea paying over 20 mil to sign Shaun Wright-Philips and Essein, thus effectively making 30 mil the new "soft" cap (Van Nistelrooy, for example, cost 29.5 mil, Robinho 24 mil and Fernando Torres cost 26 mil).
In 2008, Manchester City was taken over by the Abu Dhabi Group. They made a statement of intent by capturing Robinho for 32.5 mil while also signing players like Jo and Ni Gong for almost 20 mil. Of course, the madness doesn't stop there as Real Madrid smashes the world record transfer for Kaka for 68 mil and Ronaldo for 80 mil. Barcelona followed suit by offering 59 mil plus Eto'o for Ibrahimovic. At the same time, Manchester City continued their shopping trend by getting Tevez, Adebayor and Lescott for over 20 mil while Santa Cruz and Toure (Kolo) cost close to 20 mil. What does this lead to? This actually means the price of your standard average players (the ones that can do a job but not excellent in it) has risen to 15 mil at minimum (which is ridiculous when you remember that Alonso cost Liverpool 10.5 mil). The two La Liga clubs has also shown the world that for the "top-class" players, you have to pay ridiculous money, which is shown when Torres was eventually sold at 50 mil and his replacement, Carroll was valued at 35 mil. At this point, fees around 30 mil was standard such as Aguero for 38 mil, David Villa for 40 mil, David Silva for 24 mil and Edin Dzeko for 27 mil. The new "soft cap" is now 50 mil for the average club .
In 2012, Monaco shook the transfer market with a 60 mil purchase of Radamel Falcao. One year later, Edinson Cavani was sold to PSG for 64 mil. What this transfer means is it puts the selling club into a much stronger position as they can now demand exorbitant fees for assets they do not want to sell. The Bale transfer saga which would eventually make Bale the most expensive football player ever at 91 mil was proof of this. A few months later, it was reported that Barcelona had cheated on the fees they paid for Neymar, for instead of the 57 mil reported, they actually spent closer to 75 mil instead. This actually set a new precedent that top players (stars) are now priced at 60 mil or above, unless they only have one year left on their deal. This information is used by Liverpool to push up the price of Luis Suarez, who was valued at 40 mil the season before, to 75 mil. At this time, the price of players continued to undergo inflation as Kroos, who only had one year left on his deal, cost Real Madrid 30 mil. The transfer of James Rodriquez to Real Madrid for 70 mil is further proof of this "standard price". Angel Di Maria, who was unwanted at Real Madrid, was sold off at 59.7 mil, which again adheres to the 60 mil rule. The fact that PSG continued to spend money since 2012 (e.g. David Luiz (50 mil), Di Maria (44 mil) and Thiago Silva (42 mil) ). Transfers of this kind again raises the price of average players such as Liverpool's purchase of Adam Lallana (25 mil) and Christian Benteke (32.5 mil). Man Utd were not spared as they were forced to part with 30 mil for an 18-year-old Luke Shaw, who only had a full season under his belt.
2015 is a year where 30 mil becomes the standard fee for "potential stars" while 50 mil becomes the go-to rate for "potential stars" who have had a great season. Players like Memphis Depay (31 mil), Roberto Firmino (29 mil), Raheem Sterling (49 mil), Kevin De Bruyne (55 mil) and Anthony Martial (38 mil rising to 58 mil) were stand-out examples of this trend. With much more money available, smaller clubs had more money to spend (Newcastle United spent close to 80 mil, which was unheard of previously) which of course again caused further inflation. One year later, China entered the market and started spending ridiculous amounts of money (31 mil for Atl Mad benchwarmer Jackson Martinez, 25 mil for an unwanted Ramires, and Griazannio Pelle (6th highest paid footballer in the world) ). As a response to this demand, clubs now have to even overpay on potential stars. While 27 mil for Embolo might not seem too high, fees over 25 mil is (imo) rare in the Bundesliga. Renato Sanches, another 18-year-old cost Real Madrid 38 mil while Barcelona bought Andre Gomes for 50 mil. For comparison, Hummels, an established star who only had one year left on his deal cost 34 mil. By this point, you really have to wonder how much money would you need to sign a player who is on a longer deal. Man Utd gives us the answer; 120 mil. Of course, this sets a precedent of paying way over the odds for a player on a longer deal (such as Higuain). You have to wonder how long before the money finally runs out. Remember, when a record fee is set, the fee around the players will rise. The Higuain fee, for example is higher than Ronaldo's and Bale's.