Music is one of the channels through which God's Word is delivered to His people, just like drama, teaching, and preaching. There are pastors, prophets, apostles, evangelists, and teachers who carry out God's assignment through music. This is why music is also a recognized ministry, through which ministerial gifts can be exercised for the edification of the Church (Ephesians 4:11-12).
However, no ministry, including the music ministry, should be commercialized.
On the other hand, those inviting music ministers for programs should be considerate. They should understand that these ministers have crew members to take care of, equipment that needs maintenance, and transportation costs, among other logistics. It would be unfair to neglect these realities. While it is believed that God, who gave them the assignment, will provide resources and take care of them, it is not wrong if you are the vessel He chooses to accomplish that. The same God who inspired the organization or church to invite the minister has also made provision through them to support the minister and their ministry—without waiting for them to request a specific amount before doing what is necessary.