Michigan Compiled Laws, Chapter 124. Municipalities § 124.418

Sec. 18. All concessions granted by the authority for the sale of products or the rendition of services for a consideration on authority property shall be awarded only pursuant to written specifications after competitive bidding and to the highest responsible bidder in a manner similar to that required by section 17  1 relating to contracts for procurement involving an expenditure of more than $5,000.00. This requirement for competitive bidding shall not apply to any concession involving the estimated receipt by the authority of less than $1,000.00 over the period for which the concession is granted.