All services under this subchapter and ch. 48 and all community-based juvenile delinquency-related services under ch. 938 purchased by the department or by a county department under s. 46.215, 46.22, or 46.23 shall be authorized and contracted for under the standards established under this section. The department may require the county departments to submit the contracts to the department for review and approval. For purchases of $10,000 or less the requirement for a written contract may be waived by the department. No contract is required for care provided by foster homes that are required to be licensed under s. 48.62. When the department directly contracts for services, the department shall follow the procedures in this section in addition to meeting purchasing requirements established in s. 16.75.