Looking for a business development co-founder

As a start up that has already a development team and a product in beta status we are looking for a co-founder that could bring the start up to the next level.

I found some resources about how to find technical co-founders but nothing about business developers. Any ideas where to start?

If you're looking for a person, I would go for a sales professional, someone that is able to find customers and close sales.
But there are other options, check out Seth Godin Understanding Business Development.

I'm a software developer and I spent MONTHS looking for a good business co-founder.
Biggest problem: they all have their own ideas that they want to pursue. They will never be as passionate about your idea. Well maybe you can sell your idea to them, but then you don't really need them. Go and sell the product yourself :)

In my case I just started to sell myself. You can't imagine how much valuable information you hear from customers once you start selling. After you get some traction - I guarantee that many business people will come to you themselves. By that time you should have enough money just to hire a salesman.