As of 2016, packages valued under 800 USD enter the US duty-free.
https://www.cbp.gov/newsroom/nationa...-increases-800
Packages over 800 USD are dutiable on the entire value of the shipment. I'm not sure where you got the idea that items from Europe are subject to 100% duty, because they're not.
Your method works, but I'm surprised you can't find a grey-market seller willing to ship directly to the US so you can also avoid 19% German VAT.