This paper combines the transaction cost model, the sales ethics model and the service quality model as the theoretical foundations for evaluating house buyer satisfaction with their real estate advertising sales agents. This study uses a convenience sampling method with the population of sold-out building projects and new home projects in all administrative areas of Kaohsiung. The empirical results show that the reasons for agency problems and transaction costs affect the transaction costs of house buyers and the ethics of advertising sales agents. Furthermore, agents who provide better service are associated with more satisfied house buyers with stronger intentions. Finally, sales ethics have a significant influence on transaction costs as well as customer satisfaction and complaints.