You should check out contract manufacturing. Many of these types of small jobs can be handled by a CM in China. The problem with any physical device is cost--cost in materials, machining, tool building, assembly, etc. This means you'll probably need to get some form of financing. You may be able to do a small run for not too much (10's of $k), depending on the device. This is why I always opt for bits over atoms these days.
By the way the first place to look for money to pay the manufacturer is the manufacturer itself. They need you as much as you need them and will often provide cash for equity if order from them.
