Is there all fin types available in giant bettas as in splendens?There are fish called giant Bettas, which are a different species to Betta splendens and they have a different temperament to B. splendens.
Now supplies sell XL, or jumbo or giant Bettas, and these are usually B. splendens that are bigger and older than the normal fish seen in shops. You do not want to buy these big old fish because they are nearing the end of their life.
If your local pet shop had "Giant Bettas", ask them what species they are or take pictures of them and post here.
Its bit a personal question but how old are you colin?There used to be the normal long fin types for the giant B. splendens and they have probably increased the number of fin types over the last few years. However, I haven't seen any for the last few years because I haven't been to a pet shop during the last few years.