The latest offer of €17m has been rejected by the Hoops.
"It’s actually been straightforward with Matt because he’s such a great professional,” Rodgers told Sky Sports.
“I think what is always the challenge for teams coming to a team like Celtic is that they can place a value on the league and not the player. I’ve already told the club that.
“We all understand the model here – players will come in and develop. It’s not a club that you have to move on from, but there are riches in other leagues much richer than ours that allow players to go and improve the conditions of their lives.
“We all understand that, but it’s really important that if a player does leave here we are paid for the value of the players, and that’s sometimes something that cannot happen.
“Sometimes a value will come in that’s a lot less. I’ve worked in the Premier League, I understand the levels there and the players’ value. No player will leave unless it’s for the right valuation. At this point in time, there’s been no team that’s been anywhere near it.”