Agreed - delivery is the important aspect, when it comes to just-in-time order fulfillment. If they don't deliver, then you don't deliver either. On your last

Agreed - delivery is the important aspect, when it comes to just-in-time order fulfillment. If they don't deliver, then you don't deliver either. On your last point, I agree again: scale is critical. You describe something that might work once, given that there are no supply chain screw-ups or customer service problems. At the scale you describe, you can probably absorb any costs associated with these problems, but you will eat into your time and/or profit to do so. My whole point is that the risk doesn't disappear just because you haven't invested any capital; you've just shifted the risk.