Arsenal paid a "huge price" when they decided to keep Alexis Sanchez on Deadline Day, according to Arsenal manager Arsene Wenger.
Wenger rejected multiple bids from Manchester City for the Chile international, the highest of which totalled £60m, after failing in his attempt to sign Thomas Lemar from Monaco for £92m.
Sanchez can leave the Emirates for free next summer when his deal runs out and Wenger would expect a replacement to cost in the region of £70m.
"You take Sanchez into the final year of your contract, you sacrifice £60m-£70m income and then at the end of the season you will have to buy somebody for that amount of money," Wenger told beIN Sports.
"So it has a huge price. So at some stage you have to make a decision you have to sacrifice one or two [players]."
Wenger has recognised the growing trend of players running down their contracts in order to engineer a move away from their club. Alex Oxlade-Chamberlain made a £35m Deadline Day move to Liverpool after rejecting a new deal at Arsenal worth £180,000-a-week.
Arsenal have been forced to sell to a rival before, in 2012 they sold Robin van Persie to Manchester United for £24m after he refused to sign a new deal at the club with just one year left on his contract.
Wenger believes the sums of money spent on players now is "completely disconnected to reality and the truth", citing the transfer of Ousmane Dembele from Borussia Dortmund to Barcelona for £135m as a key example, with the France international costing the German side only £13m last summer.
"We have today 107 players in England who go into the final year of their contract," said Wenger.
"It's a complete rotation and change in the way people see their careers for two reasons. One, all the players expect higher wages because they anticipate inflation; [and two] because the transfer market has gone up so much but clubs do not want to pay so high prices on transfers for players who are good players but will not change their life.
"The amount of money is completely disconnected to reality and the truth. I give you one example: no matter how well you work as a football coach, Dembele last year was €15m, this year €150m. No matter how well you work on the football pitch you cannot make a player go from €15m to €150m.
"But the calculation between investment and what you can get back has gone. It's just: can you afford to buy or not?"
Sanchez, who is set to return from international duty this week, could be in line to play for Arsenal against Bournemouth on Saturday.