Afaik, it's not competitively priced for large volume. We priced around 650 users for box, and it came out to be roughly $8K annually. At $5/month/user, the Amazon offering would be roughly $40K annually. I'd actually prefer to go the Amazon route, but they're going to have to offer volume discounts to make it compelling.
If you have 650 users (who I'm assuming are paid employees), doesn't the cost become marginal in comparison to improved productivity?
I would guess the time to re-train all 650 on a new platform and the ease of transferring existing files would be more meaningful than the price difference.
I'm actually waiting for clarification on this...I think my team might've misinterpreted the quote, and if so, Amazon would be significantly cheaper. I'll update as soon as I know (most likely Monday).