Used Arduino to prototype an idea. What's next?

I had an idea for a home device that would measure some elements (temperature, air pressure, humidity ...) and report periodically to a remote server for analysis and advice to the home owner.
After building a prototype with Arduino, I'm satisfied with the results.
How do I proceed in order to actually make this device into something commercial (smaller, cheaper, mass-manufacturable)?

Thanks

I should have googled better :confused:

Here's a set of answers I just found: