No one wants to built it themselves until people actually want it, if your device is popular then your device is $2 on AliExpress/eBay and you have no part in that, look at Arduino for a good example.
This...if it's successful, a knockoff of your device will end up on eBay, AliExpress, Amazon, etc, often with sketchy parts, at a price you'll never match. With some exceptions, where you're able to make the product depend on a hard-to-get-cheap part, etc.