Think about this for a minute. DwarfMiner can finance 90% of the production cost out of their own pocket. Why do they need to do this preorder bullshit at all? They could just do a run of 5000 units and sell on a product-in-hand-ships-tomorrow basis.
Again, why would a supposedly legit business do everything possible to look like a scam?
Everything looks like a scam for you

As I can understand, they took part of the payment for large orders only. Batch was prepaid, they wrote about it.