I need a location based search function for existing property website

General information for the website: a property wordpress template site requires a more advanced search facility

Kind of development: Customization of existing website

Description of requirements/features: Currently the website template has only a predefined list of locations that are put into the database when the administrator adds a new property for the site. The user can only see a list of these predefined locations. I need this to change so the user can enter a location, e.g. a town or postcode. The search then looks for properties near to this location and displays the results in a list. We also need an option so the user can chose proximity to the locations e.g. 1 mile, 5 miles etc. This will need to work with the already existing search criteria.

Also it might be a requirement to show these on a map as well. I believe the method for this is to use something like the Google Geocoding API. The website is a template and can be found at http://wpestatetheme.org

Specific technologies required: PHP, Wordpress, Google & Geocoding API

Extra notes: This is often used for store locators to see how many stores are close to an entered address or postcode.

Here's some possible useful information https://developers.google.com/maps/articles/phpsqlsearch_v3

Also see rightmove.co.uk for an example, although will not need the complexity of this search option.

http://www.rightmove.co.uk/property-for-sale/find.html?searchType=SALE&locationIdentifier=REGION%5E93980&insId=1&radius=1.0&displayPropertyType=&minBedrooms=&maxBedrooms=&minPrice=&maxPrice=&retirement=&partBuyPartRent=&maxDaysSinceAdded=&_includeSSTC=on&sortByPriceDescending=&primaryDisplayPropertyType=&secondaryDisplayPropertyType=&oldDisplayPropertyType=&oldPrimaryDisplayPropertyType=&newHome=&auction=false