Not really a rant, but maybe someone can help me on this one.
Me and my brother are thinking about creating our first app. We know what features we want and also how the workflow of our app should be (we even sketched the workflow with an online mockup tool). The programming of the app itself is no problem, but we are both struggling when it comes to create a nice looking, smooth design from our draft. As we both believe that a nice looking UI is important we are not afraid to invest a little bit to get a nicely designed UI - "Make it right, or don't do it at all" ;-)

We searched a little bit in our hometown and found a company that would design us something for at least 15-20k Euros. As we do already have a pretty detailed sketch and also would need to pay that from our own pocket (we do not know if it gets more than a hobby project) its definitely too much for us. So my question is: Are their any app design companies out there that takes a sketch and creates a smooth design from it?