This study aims to compare the cost-effectiveness of an online teacher training method with a face-to-face training method in teaching "ICT integration in the school curriculum". In addition, the study explores the possibilities of a school-based voluntary training method in supporting other approaches to ICT teacher training. The analyses of various quantitative and qualitative data showed that online teacher training was more cost-effective than face-to-face teacher training, mainly due to the lower opportunity cost of the participants. The voluntary teacher training revealed the possibility of providing cost-effective training, especially in the actual application of ICT in classrooms. Based on the results of the study, factors affecting cost-effectiveness of the teacher training approaches are discussed and further research areas suggested.