Dealer Locator search needs zip codes, nearest dealer

An existing search feature needs to be enhanced. We need to let the user get results for the locests result, even if it doesn't fall into the exact query. There are a total of 5 identical sites that need the function. Development here: [login to view URL] I understand I need to buy an additional database for zip codes. Please let me know your experince. This will need to be done this week.