It is an off-beat anniversary, for a gallery that is always done it its own way. The 100 Market Gallery is celebrating its 18th year as the sole patron-sponsored, artist-direct gallery on the Seacoast, if not the State, with “Legends”. The 100 Market Gallery's initial exhibits were invitational, before a juried process was established. “Legends” features a collection of those earliest artists, each regionally renowned in their field. Michael Simchik had few stipulations when establishing the 100 Market Gallery, with…