If you are simply looking to get some iOS experience, you should be able to hack together the UX/UI yourself. If you are trying to launch a business, design will be imperative for success. Show me 1 poorly designed, truly successful App in the App Store.
Like everyone says now-a-days... I'd suggest focusing on the MVP concept and build just the core features, with excellent design and UX.
For inspiration: http://pinterest.com/timoa http://www.mobile-patterns.com http://pttrns.com http://www.lovelyui.com http://iphone.meer.li http://www.awwwards.com/inspirational-and-useful-resources-f... http://uxarchive.com
(It's important to have at least a basic understanding of the platform's UX guidelines, even if you leave the detailed work for someone else.)