Exteneded sort based on location

Hi There, I have desperatly trawled the internet looking for something similar to what ebay have where product selection can be sorted based on their location.
So they have done their product search
All items have been listed
they can then filter that to sort based on their location.
my question is is there anything like this available or indeed do you know of any developers we can pay to put this together for us.
help would be greatly appreciated as this function is integral to the business
Cheer
Claire