First, the current study aims to identify the determining factors of the purchase price of sportswear worn by runners. Second, this study aims to demonstrate that diary-methods can be a useful method in sports consumption research as they provide in a large amount of data on a very detailed, non-aggregated level. Based on a dataset of 2,235 running sessions of 192 runners, the results indicate that one fifth of the total variation is due to differences between running sessions of the same runner, instead of between-runner variability. It is found that a runner wears a more expensive outfit at a running event session when compared to a training session. Runners with a higher educational level, income and who run in a fitness center or a health club wear more expensive sports apparel than other runners. Both the regression results and the innovative diary approach bear interesting implications for runners, running enterprises and researchers. For example, implementing running consumption in smartphone tracking applications could improve the running experience, which on their turn provides in big data for further research.