The program your describing sounds like something that might be available off the shelf. I think the official name for that type of software is Enterprise Resource Planning(ERP).
If this software isn't available off the shelf, then you should contact a software consulting firm in your area. The big boys are the Accentures, IBMs, but there are thousands of mom and pop computer consulting firms (firms < 1000 employees). To ball park prices I'd guess the following rates for a team of programmers (all rates are hourly USD):
Project Manager: $250
Tech Lead: $250
Programmers: $100-150
DB admins: $150+
It would be hard to guess the workload involved without details, but I'd say most development projects with about 7-10 people lasts anywhere about 3 months to 18 months. (The project I'm currently working on has a 6 developers and a budget of 4 million dollars for a fiscal year).
A few issues you may have overlooked:
Who will maintain your system?
Who will perform the back ups?
Who will fix your problem when a bug is discovered?
Who will install this system if you ever upgrade to new hardware?
I can't be assistance with offshoring, but usually only the Accentures and IBMs do that. You might find a middle man, someone that knows some Indians(Ghandis not Sitting Bulls) and can speak the language.
As for keeping your ideas secret, most companies that hire outside consultants to develop an application for them make them sign a non-disclosure agreement. Seriously, order/customer/sales/inventory tracking aren't novel ideas. Every company uses some kind of software for that. I'm skeptical that what your thinking of has been done before. Just my 0.02.
If your still interested I would contact a local computer consulting company or talk to a free lance project manager. They could give you some definite answers.