Might not be quite the types you are looking for, but I've noticed recently that the pets at home stores near me have recently upped their betta game big time; they now stock dragonscales, crowntails, koi, plakat etc with some superb colours
Colin Dunlop at the fish hut, Carluke also has stunning Betta splendens of show quality.
Just message Colin (or Lisa - request to join her FB page) & indicate your interest/preference