Geo IP visitor location module for dating site

we have a new dating site. [login to view URL] and what we want is a similar feature to the landing page of [login to view URL] \basically when a new visitor arrives at the site, the site recognizes the visitors location via IP and based on the location the site shows a list of members from the same city that's it. i understand we may need a 3rd party IP database, we will cover cost of this...but you need to set it up and suggest best vendor for this thanks garfield