Not sure how rare these are in your country. I would not buy such a low quantity unless they are very hard to source. And when buying, do get all your fish from the same source at the same time so you get the same strain even if you can't accurately identify them. Do have a long hard look to see if several different strains - sizes - differences have been mixed during the collection/import/wholesale process. Don't add more fish from other places later.
If your not out to breed them, it doesn't matter what sex, size, condition, variant they are of course.