How to change price in shop based on location? If in US then US dollars etc
Start your search at Commerce Multicurrency and find ways to detect the customer's country from there. Here is an excerpt about it from the module's project page:

... enhances some of the multi-currency capabilities of Drupal Commerce.
Current features:

UI for fine granular definition of exchange rates.
(Every currency combination can be defined separately if needed)
Synchronization of currency exchange rates directly from the European Central Bank (ECB).
UI to specify which rates shall be synchronized and which are handled manually.
Generation of currency specific price fields inclusive generation of rule-set to handle them.
hooks for easy integration of custom currency exchange rate sources.