Salah has been linked with a move away this year.
Murphy said, "You'll have to bring in a superstar, you'd have to bring in someone who's got the quality.
"I don't think at the moment there's too many out there who you'd put above Salah in terms of numbers and ability to win matches and score goals.
"Yeah if you're going to break the bank then maybe a Sancho or even Mbappe they could try and go for, whether they can afford him or not I don't know.
"But I think Liverpool will be planning, they've done tremendously well in the recruitment area for a long time now.
"With the rumours, with the ages of the players, it would be remiss of the club not to be looking at what they could bring in to push and maybe take the place of the players you're talking about."