I have encountered similar challenges when both hiring for a company on a tight budget as well as when implementing my own product ideas. There are a few paths you can take here depending on what you are trying to create.

For well-known domains with tight specs, you can go with fairly inexpensive contractors offering their services via elance.com or odesk.com.

If you have a high level vision of your mobile app but still need to identify product market fit, you have a couple options:
1. Build it yourself even if you don't have a technical background. The barrier for entry on mobile prototyping has been lowered thanks to WYSIWYG editors such as Appery.io which will work across Android, iOS and Windows Phone platforms.
2. Participate in a Hackathon. Folks at most of these events are young, friendly and looking to network. So if you have a compelling idea and can offer value towards the project (i.e. design, art, etc), you will find many like-minded folks who are willing to pair up with you. If you are not located in a tech centric city, you can always join virtual hackathon events via Hacker League https://www.hackerleague.org/.

If you have additional questions, ping me via clarity and I am happy to discuss further.