Why would you pay that much for a costume when you could make your own for like 50
Because most people don't have the skills to do that? And don't want to spends hundreds of hours/thousands of dollars investing into practicing?
Also these aren't children/women paid pennies a day in 3rd world countries like most clothing, these are artists who actually want a livable pay/hr, and it takes a lot of time to make these.
Also $50 won't get you anything lol
A yard of faux fur is like $25-35 for basic stuff, even more if you want really long pile or a hard to find color. And you'll need several yards, in multiple colors
Plus you need a ton of other stuff like sewing supplies, a ton of hot glue, foam.
Just the materials can easily cost several hundred.