you can also order the ones from Pinball Life as they're the same size.
don't forget, all new buttons lack the e-clip that older buttons had and will often wear out quickly as they're held together with just a small plastic ridge on the shaft. you can get e-clips pretty cheaply at most pinball retailers as well as hardware stores, and snap them on. i think the ones that fit are the 1/4" but i don't recall for sure.