The former Arsenal midfielder believes Jose Mourinho would take the Manchester United flop for the right price.
The Colombian is currently on loan with the Red Devils from Ligue 1 side Monaco, but has failed to settle at Old Trafford and has often struggled in the games he has been afforded.
Any deal to sign him permanently would be a costly one for any suitor, with Monaco likely to want a large sum for a player they paid a big fee for, while he is also on lofty wages.
However, Merson says that the current Premier League leaders would look to take him should he be available on the right deal.
“If he went down to £15m, I think there would be a lorry load of teams after him,” he said.
“I think Chelsea would take him at £15m, they need another centre forward. Whatever happens next season, to be successful in the Premier League and Europe, they need another centre forward because when Costa isn’t playing they miss him.”
The former Arsenal midfielder has also defended the forward after his so far unsuccessful stint in England, saying he will one day return to his former status as one of the world’s best.
The South American was one of the most ruthless strikers in Europe during his time with Porto and then Atletico Madrid, with a hat-trick against Chelsea in the UEFA Super Cup a particular highlight. However, a serious knee injury saw him miss last year’s World Cup and has arguably curtailed him throughout this season.
“He is a good player and I think he will get fitter and fitter,” he added.
“He needs to player football and then I think he will get back to where he was. He was one of the best centre forwards in world football.”