Thank you to everyone who gave me information about other companies
practice of reimbursement for participants in the medical domain. I
also asked the same question on another mailing list, so here I give
you the short summary of the responses. If someone would like to add
or comment, I still appreciate every information on that!
Summary
The FDA states that "it is not uncommon for subjects to be paid for
their participation in research, especially in the early phases of
investigational drug, biologic or device development.