The simple answer is:
To weed out those who won't even pony up such a small amount for something they claim to support.
The more detailed answer is:
Because it's a LIFETIME membership and will have to cover all administration costs regarding your file for the rest of your life/membership. I know the kiddies don't believe it, but there are distinct advantages to being a member, at least if you put any further effort into it, and to expect them to do all this for free is ludicrous.
But, you're not required to join. If $200 is more worth than Satanism has contributed to your life, then I not only suggest you save your money, I actively discourage you from joining.
"The devil I'll bring you," answered Hagen. "I have enough to carry with my shield and breastplate; my helm is bright, the sword is in my hand, therefore I bring you naught."