I also am not associated with the seller, but I do know Macrobrachium shrimp.
Those are a species of Macrobrachium shrimp. There are many undescribed, or incorrectly described species of shrimp. I approve of the way the seller lists the shrimp. They are not claiming to know the species, and don't provide a meaningless common name. Though the seller does not mention the temperament of the shrimp, this I would change.
As for ease of breeding and the price; they are expensive because there are very few of us who breed Macrobrachium shrimp for hobbyist aquariums. I used to breed and sell Macrobrachium shrimp, but I've stopped. I still keep three species, but I no longer sell them.
There are two types of Macrobrachium shrimp. The first type produce young that must grow in an estuary (brackish water), and mature through approximately 7 to 9 larval stages. These are very difficult to breed in captivity, requiring multiple hatcheries and specialized food and vigorous testing and monitoring. The second type either have abbreviated larval stages (1 -2) or no larval stages at all. They do not need brackish water to mature and are much easier to breed by hobbyists.
Another thing to be aware of, Macros can be very aggressive. Larger examples, say 5 to 12 inches, will kill ANYTHING in the tank with them. The smaller species, those less than 3 inches, are not aggressive fish hunters. However, they are aggressive towards each other. They establish a social hierarchy, with a dominate 'Alpha Male' that rules the tank. He controls the adult females, and will attack other males that mature. They usually go after one another after molting. If you have a large enough tank and sufficient hiding places, two alpha males can mature in a single tank.
I highly recommend Macrobrachium shrimp, but be aware of what you're getting, and how to keep them.
