All of my equipment is hunter green with gold trim and cream piping. I bought my equipment at a time I knew I would be imminently changing barns as I was moving, and figured I might as well buy colors that looked good on my horse. It happened that the next 3 farms all had green as a base color, so my equipment wasn’t ordered out of sight at shows.
My current farm is navy, Carolina blue, and white and black trim. Matches everything and it’s not hard for students to find stock coordinating options- lots of our kids have Dover’s gray, navy, and light blue dress sheets, for example, which fits right in without breaking the bank. Getting the Carolina blue right on vinyl trunks and drapes was apparently a bit of a job, though, as for some companies it was a custom color.