I am planning to start my own business and need a web developer but I am not sure what kind of qualifications I should look for. Can someone please help?

Here is a brief description.

I want a web site/application that has a design similar to Groupon.com (clean, to the point information). The main goal of the site is providing comments of people about a service/person (this will be more specialized, for instance specialized to mechanics, but in general it is the point).

In the web application, guests
can be a member
can see a portion of the site content (a portion will be seen and the rest will be blury, and there will be a notice stating that if they become a member, can see the rest of the content)
can search in the site content through an advanced search page
On the other hand, members
can enter the information of a service/person (e.g. can enter the basic information of Walter auto mechanic.) in a city or neighborhood
can search for a service/person (e.g. can search for the basic information of Walter auto mechanic and see if there is any comment about this mechanic or not)
can search for general service at a neighborhood or city (e.g. among the mechanics, those specialized on breaks or among the mechanics, search for those who has a rating over 4)
can rate and make comment about the service of a service/person (e.g. can make comment about how satisfied he/she is about the service. just like trip adviser but for e.g. mechanic)

I also appreciate any web developer referral.