How to change price in shop based on location? If in US then US dollars etc I really hope that someone can help me out here..

We set up our shop with drupal commerce, but we ran into a problem regarding currencies..

On old shop (Custom) we had option enabled if visitor is in US, currency will be set to US dollars else GBP.

Any advice on that? Im sure that somehow this could be done.. Maybe with geolocation?

Or if you have any other ways to do this, I will be happy to see what we can do.

Thanks for any advice!
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.