I Googled "Is Arbonne a cult?" I found two responses that I liked:
A Modest Proposal. In which a former Arbonne rep advocates laying out the true costs and true expectations for new sales reps before they sign up.
Arbonne: An Example of Multi-Level Marketing. This one talks about Arbonne and Amway and the evils of multi-level marketing in general. But it's not nearly as bad as it could be.
So after reading that, I don't think Arbonne is quite a scam. But also decidedly not a get-rich-quick scheme.
The industry opinion seems to be that the products themselves are over-priced but very good. The facts that you have to buy-in and that online sales are not allowed, however, are a red flag. Moreover, most of the higher ups at Arbonne have deep discounts, allowing them to sell on EBay, which is what's necessary at the upper levels for prolonged success. The company understands this and tolerates it because they have no reason not to. Moreover, Arbonne's primary revenue actually comes from new sales reps buying into the business rather than from actual sales. That's essentially the Amway model, which is why the company itself has an unwholesome image nationally.