making money from custom built iPhone apps

The price of mobile custom built apps varies significantly from customer to customer based not only on the techical requirements of the app, but on who the client is.

I consider targeting Shopping malls and building something like enter link description here What price range would you give for this app?
$5k-$10
$10-$20?
How much do you think they paid ot this app?
I would ask around 6k for something like that, considering the fact that

Pricing of app development depends on these factors:

• the skills required
• the amount of work to be done
• the amount of time it takes
• how soon the client wants it done
• expenses incurred as part of the development process
• competition for the job
• final quality and completeness
• whether payment is upfront, revenue sharing, or a combination of the two (probably all upfront in this case)

I really don't have a ballpark figure. Mass-market retail is a difficult business, and the people involved may not understand or care about mobile apps.