This starts at $50 a month and goes up to $200 a month for certain "ranks".
If you cannot sell $50 of Avon products in a month, you will need to buy $50 of Avon products yourself or your account will be suspended. Any future sales you make won't be credited to you.
So for your first year with Avon you need to allow a total cost of:
First year minimum costs: $625 - $700
This is before you think about any other marketing costs such as an email autoresponder, your own website (not just the replicated one you get from them), paid social media advertising or packaging supplies.
If you do sell $50 of product each month then you aren't required to buy anything yourself... but many people are not aware of this when they join.
It's clearly far less than starting a "normal" bricks and mortar business like a restaurant, but it's certainly not "free".