I did the UI design myself but paid ~$300 for the actual graphics (image buttons, icons, backgrounds, logo, etc.).
If you don't mind recommending the designer, I'd love to know who did it.
With regards to getting more users, you should at least look into how much it would cost to buy keywords such as "cab sharing" that are targeted to iOS devices. This is a purely anecdotal datum but I don't see any ads when I search for cab sharing on Google so there may not be much competition.
The key question is how you can make enough revenue per user to justify acquisition costs.
Actually... could you outline your process of finding the designer? What was the workflow like? Did you send him your .nib files and let him go to town, or did you send him screenshots, or what?
1) I already had the general UI layout I wanted 2) I was very specific on what I wanted (from color schemes to font sizes, etc) 3) Iterated very quickly - since I outsourced the work and they were in India, I would stay up late to be on the same schedule as they were and give them sub 5 min feedback whenever they sent out a design
Here was my general process:
1) Wrote the server code, agnostic of client
2) Started writing UI code in in Objective C. This was a mix of programmatic UI code and interface builder. But I designed the UI from scratch, didn't really do mockups just coded directly and refined by testing on device (imagining where I would have pretty graphics in place).
3) Recruited a designer on elance based on their portfolio. I would send you the link but they no longer seem to be active on eLance.
4) Sent them screenshots of my current ugly design plus detailed spec of exactly what I needed on each screen (i.e. background, a logo, buttons, icons, etc). If you are interested I can send you the spec I sent them (aleem.mawani at g m a i l)
5) Made sure they sent me high rez PSD files of the screens they designed.
6) Used photoshop to export individually the layers I needed. This was the most painful part.
7) Plugged those images into IB or code directly.