Budget and overall general skills that would be needed on a project. BUT, if your main reason for partnering is budget and you are confident that the project will be successful, why not take out a loan?
The reason for taking a partner is to bring in something you dont have... normally this will be skills/ experience, money or time. If you are 100% confident of the success and are good at making others agree this then a loan is another option instead of a financial partner however most prefer spreading the risk over more people in case it goes belly up.
Another thing you could do is do odd-end jobs such as writing and forum posting to gain some money. There are several of these types of projects in the Buy, Sell, Trade section. Once doing this, turn around and invest that money into your project.
The thing with doing the writing and forum posting is that you don't really gain much and it could take you a good few years before you get your start up capital if you needed $10k or more to get it started. It's a good way to earn some extra money to put towards it or even start it up if it doesn't need much investment.