Are Betta Fish With Red Eyes Rare?

I'm asking because I came across this red-eyed Betta fish being sold. He only has one red eye while the other is black, and I'm seriously considering getting him. However, they're claiming it's rare and while I'll say I've never seen a Betta fish with a red eye before, I'm wondering if it really is? Doesn't matter if it's rare or not to me, he's interesting looking and either way I'll probably end up purchasing him.

 

I wouldn't call it rare as I've seen plenty of bettas with red eyes before, but maybe it's uncommon where you are. It's more common in red coloured bettas.

 

This one is white. It has one black and one red eye.
Either way, I've never seen a red-eyed betta before.