Jadnashua
Retired Defense Industry Engineer xxx
There are two things in a typical toilet that wear out: the rubber flapper (around $10 if I remember - depending on your water and how much clorine there is anywhere from a few years to many), and, on the Toto's that use the Korky valve, a rubber seal (about $2.50 - could last many years; maybe less if you have a well and get grit in your water). Both are readily available at Lowes and most any plumbing supply house, or on-line.