Different pricing of apps regarding regions in country
You can use the promo codes


  You can request up to 100 promo codes for every version of your app. To request promo codes for an app version, the version’s status must be Ready for Sale or Pending Developer Release.


https://developer.apple.com/library/ios/documentation/LanguagesUtilities/Conceptual/iTunesConnect_Guide/Chapters/ProvidingPromoCodes.html

You can send gift


  Learn how to send iTunes Gifts in the iTunes Store, iBooks Store1, and App Store. In the iTunes Store, you can gift a dollar amount or books, audiobooks, music, movies, TV shows, or apps from your iPhone, iPod touch, iPad, Mac, or PC. Use these steps to send a gift from the iTunes Store.


https://support.apple.com/en-us/HT201783

Or you can use the Entreprise Distribution and make the price by your own for every client.

http://mobiledan.net/2012/03/02/5-options-for-distributing-ios-apps-to-a-limited-audience-legally/