I think more details are required! What are you willing to pay? How big is the project? Is this one of those lame "I had this great idea: you do all the work and we'll split it 50/50"? Because if so: ideas are cheap and plentiful: and idea is only worth around 5%.
Instead of splitting a portion of the money, you'll have more success if you offer a flat rate. Most of the time when I approach new projects, I find the idea iself flimsy and half-baked. It is for this reason that I would never go halfsies (or any other ratio) with somebody I didn't know.
Just for reference, a novice developer makes about $50k per year, and Senior devs make $100k+ or more. So if you want somebody with talent AND experience, and you expect to need them to work for you for 6 months to write this software, expect it to cost you $35-50k.
If you're really stuck on the business partner idea, however, I would suggest you write up a real business plan.
But yeah, Robbie is correct. We see occasional posts like this saying "I have a great idea, and if you work for free now I'll throw you bread crumbs when I rule the world." There are not to many really clever ideas out there. Clever is figuring out how to implement the idea while meeting practical constraints such as marginal cost, power consumption, usability, etc.
(Think iPod vs. previous MP3 players. Nothing clever about the idea "Hey let's put a hard drive into an MP3 player!" It's pulling off the idea in one of the most compelling forms the world has seen that has earned Apple big bucks.)
