It is true that AC Milan is not a team that has a lot of money, therefore, Milan will find it difficult to bring in players at high prices. I think even to bring in players at a price of 50 million euros, Milan needs to get it from player sales. Regarding rumor about Samuel Chukwueze, if it is true that AC Milan has succeeded in signing him, then Milan must be able to sell several players first. There are several names that could be options, such as Saelemaekers, Origi or even Messias.
AC Milan is like many Italian clubs in the last few years. They don't have too much money like clubs from Premier League or La Liga. They have to look at free players to convince those players participate in their clubs. Inter Milan, AC Milan, Roma, Juventus focus on this approach and they got some success. They aim at young players, not old players if they have to spend money for transfers. Because they want to build a squad that can play in a next 5 years or longer with those players.
In addition, they don't want to increase their salary ceilings too much because they are aware that it will be harmful for for their club finance after a few seasons. If results in leagues, competitions won't maintain at good levels, a higher salary ceiling will cause a financial crisis for their clubs.