The manufacture of Raspberry Pi's as far as I am aware is by Element14/Premier Farnell. Originally they were made in China but are now produced in the UK, which is fitting, given the Foundation is a British organisation. You can read more about that here.
In terms of a Pi made for commercial use Element14 have an exclusive Raspberry Pi customization area. This would allow you to order customized Pi's in bulk orders. I've not really looked into this too much as I haven't had the need to bulk order Pi's. If you contact Element14 with your request they might be able to find a solution for you.
You might also be interested in the Compute Module, which fits in a DDR2 SODIMM connector. This is aimed at people looking to produce custom PCBs. You could probably bulk order them and try to find an electronics company to build a board with your required components.
As to another device with extensive customization support, well that really would depend on your needs. It's also a question that wouldn't be on-topic here as it's not related to the Pi and is more of a business operations question anyway.