When one's occupation is a spiritual ministry, how to deal with payment is a perennial dilemma. On the one hand, you don't want to require people to pay. That seems to reduce what you are providing from a spiritual gift to a worldly commodity. On the other hand, you don't want to go broke. And that is not some unrealistic concern; most such ministries constantly dance along the edge of a financial cliff.
What does the Course say about this? The question is addressed indirectly in many places, but is addressed directly and brilliantly in the Psychotherapy supplement, in the final section entitled "The Question of Payment." What I have to say will be mainly drawn from that section. For that reason, I will use the language of therapist and patient, but you can broaden the points I make by remembering the following:
Therapist = the one who is serving
Patient = the one being served
Healing = the service being given
What follows will take the form of six points, which start out quite abstract and move increasingly toward a concrete policy.
1. Healing is a free gift from God
The therapist may be saying and doing a number of concrete things, but the one who really heals, according to Psychotherapy, is not the therapist, but God. God moves through the therapist and gives His gift of healing. This gift must be free, for two reasons. First, it is from God "and He asks for nothing" (P-3.III.1:1; all quotes will be from this section). If the gift really comes from God and He doesn't require payment, then the matter is settled. Second, only a gift that is free—that makes no demand—is a true gift, and only that will heal the patient. The patient's whole sickness is that—both in his mind and in his world—he is locked within a system of demands, a system in which there is no love. Having a "'bought' relationship" (3:5) with a therapist merely perpetuates that system; it is just one more square in the grid. The only thing that will heal the patient is someone coming from outside the system of demands and giving him a true gift. This does not mean that money cannot change hands, it just means that the real nature, the real essence, of what the therapist does has to be a gift.
2. Both the therapist and the patient have earthly needs, and God cares about those needs
Even though earthly needs are illusions, so long as we are in this illusion, we have them. The therapist has them, as does the patient. And Psychotherapy suggests that God cares about both sets of needs. It speaks of God supplying the therapist's need for money (1:4, 5:7-8), and it speaks of God's plan allotting money to the patient (2:7). Indeed, it says that God guarantees the right to live to both patient and therapist (4:1-3). This means that whatever way payment is handled between them, it must be one that honors the earthly needs of both.
3. Payment is also a gift from God
Just as healing only seems to come from the therapist, so payment only seems to come from the patient. Actually, it comes through the patient from God. God arranges for certain patients to pay as His way of supporting the therapist. Further, this is not compensation for the therapist's sacrifices, nor some sort of statement of his divine worth. It is more utilitarian than that. God pays him to keep him on earth (1:10) and "to help him better serve the plan" (1:4). It is crucial for the therapist to realize that his support comes from God. When he thinks it comes from his patients he is unable to see them as his brothers (5:9). At that point, even if he lifts all formal demands, he will still retain a subtle inward demand: "You should be giving, or giving me more." And as we saw, such demands are part of the sickness, not part of the healing.
4. God decides who should pay and who should not
This is crucial to the practical effectiveness of this whole approach. God is looking out for the earthly needs of the therapist, and based on those needs, He sends certain patients who are meant to pay the therapist. And He sends certain ones who are not meant to pay.
5. Whoever comes has been sent by God (6:5)
According to Psychotherapy, every single person who comes to a therapist has been sent by God, because there is a potential for something holy to transpire between them, something that will bless both, not just one.
6. "No one should be turned away because he cannot pay" (6:1)
This is the punch line. In the entire body of Course material, it is the only behavioral rule we are told "should always be observed" (6:1). It follows inevitably from the previous five points. Think about it: A patient arrives needing help, but he cannot pay. Since he has arrived, we can be sure he has been sent by God (point #5). Since he cannot pay, we can be sure that he is one of those whom God has ordained should not pay (#4). This patient is the test of whether or not the therapist is really offering a free gift from God (#1). If the therapist will not give healing without payment, then he is obviously not. The negative effects that flow from this are quite striking. If the patient goes ahead and pays for this so-called healing, then all he is receiving is an illusion, since money, being an illusion, can only purchase other illusions. Further, he now has spent money God wanted him to have to support his earthly needs (#2), and those needs will suffer. The cost to the therapist who has deprived him of this money is even greater. "The therapist who would do this loses the name of healer" (2:9). Why such a radical statement? Because such therapists "make demands, and so they cannot give" (3:2).
It could have been so different. The patients who cannot pay have been sent by God to give the therapist a much greater gift: "to teach the therapist how much he needs forgiveness, and how valueless is money in comparison" (6:8). Meanwhile, other patients are sent to him for the express purpose of supplying the money he needs (6:6), and for these, paying him entails no cost to them (2:7). Indeed, both patient and therapist are blessed by it (6:7).
Psychotherapy leaves it to us to figure out the details of implementing such an approach. It doesn't, for instance, spell out how we determine if God has decided this particular person shouldn't pay—though it does imply that the telltale sign is simple inability to pay. I don't think the exact details of how this approach is carried out are important. It could be fleshed out in many different ways. I think what is important is the mindset, which is that God is the One giving His gift through you and He is the One paying you. What is especially crucial is a mindset of trust, that you trust Him to send you enough people who can pay and trust Him to send an invaluable gift with each one who cannot.