[bbatchelder]

I happen to be building this exact same product, but closed source, and somewhat attached at the hip to my company's 3PL WMS product.

One thing I did not see in your demo, is inventory synchronization. I'm guessing thats because your first use-case is drop shipping.

I'd also disagree that you're open-source Amazon. You're more like open-source DropStream or maybe Boomi.

If I were you, I'd do this:

1) Pick an open-source WMS and write a channel for it. 2) Make it dead easy to write ad-hoc channels. 3) Quickly implement shop connectors for BigCommerce, Magento, and WooCommerce.

Good luck!