464331 Regional Search Function For Wordpress Theme

I have this Wordpress theme [login to view URL] and want a regional search function that allows users to select their city first and then ONLY ads in that city are viewable like at [login to view URL] or even http://www.craigslist.com. There are several ways of doing this however I need a 100% accurate solution and want someone who has experience with this type of project. I do NOT want to buy a script I already have this one and do not just want a city or search search function since I already have a functional search. Additional information on regional search functions can be found at [login to view URL] HOWEVER IT WILL NOT WORK ON MY THEME. I just wanted to give you as much information and reference for a more accurate bid.