It could be the techniques or how they make it. I tried also making my own deodorant with baking soda and coconut oil it was an epic fail I smelled terrible. I never bought the store brand so I have nothing to compare it to.
Btw if you don't mind what brand did you use and if it works so well why not keep using it. I know you said it was expensive but if it works I am sure you could only use when you are out and stuff.