552A.3  Right of cancellation — requirement of writing.
  The requirements of sections 555A.1 through 555A.5, relating to door-to-door sales, shall apply to sales of buying club memberships, irrespective of the place or manner of sale or the purpose for which they are purchased. In addition to the requirements of chapter 555A, a contract shall not be enforceable against a person acquiring a membership in a buying club unless the contract is in writing and signed by the purchaser.
93 Acts, ch 60, §3