The reason is because they aren't going to waste money mass producing a holster that someone might buy. They will only make something they know will sell.
You'll need to have one custom made and leather is going to be pricey. Youre best bet is kydex. Take a look at blade tech. I recommend the eclipse as you can convert it to Iwb. I've got one for my 1911 and it is amazing.
Just give them a call and see what they can do.