Plenty of manufacturing firms will work with startups. They just have a strict "show me the money" policy. Once your hardware design is worked out[1], you can

Plenty of manufacturing firms will work with startups. They just have a strict "show me the money" policy. Once your hardware design is worked out[1], you can order a production run[2] of a few hundred units a month[3]. [1] They will be glad to help you design your product too. The last quote I got for an "idea to device" service was $500k and six months from zero-to-production quality. [2] As long as most of your components are tape and reel. [3] Some firms have complete facilities in the US and China. Low volume orders can be done in the US while everything else is sent to China.