Hi and welcome to the forum. Please note that any photos that are not yours must have the source credited. I had to remove the one above because the watermark had clearly been covered.

C. aurita (Brazilian Horned Frogs) are very rare in the pet trade, hence the high price. Brazil banned the export of its native species a couple decades ago. These are one of the most sought species because of their rarity, bright colors, and potential size. These are said to be the largest of the eight species. But as Mentat mentioned, I have never seen a verified picture of one that large. Size of any of these frogs vary between individuals.

I have two Auritas and they are great frogs! (One of them is my avatar picture.) If you are willing to pay the higher price then they are definitely worth it. I would note that sometimes Joazeirensis (Caatinga Horned Frogs) are sometimes sold as Auritas. These are also from Brazil but they are somewhat easier to get and not as pricey. I would verify which one the pet store has.