I'm continuously building and improving https://lectronz.com/, a marketplace for electronic enthusiasts and professionals that focuses on the open-hardware and DIY electronics communities. We recently introduced "Threshold Pre-Orders," a pre-order mechanism that lets hardware creators gauge the market before committing to production/PCBA. We have successfully tested this on four low-volume products already. See https://lectronz.com/u/lectronz/articles/introducing-thresho...