Custom ecommerce

I have a script that I want to add more features to. I purchased a classifieds script from [login to view URL] You can see an example of the script that I purchased here [login to view URL] I want to be able to charge for job postings and have the rest of the ads be free. I need to be able to set the amount for each city through the admin panel. I want to use the oscommerce script to do this. Instead of using the oscommerce script to sell products I would like to use it to sell job postings. After checkout the job ad must post to all cities that were paid for. It needs to be easy for employers to post to multiple cites if desired. I need to be able to control how long the job posting will listed for through the admin panel separate from the rest of the ads. When finish the job posting section should be similar to [login to view URL] but with the ability to set different prices for each city. I also would need to be able to set up different categories for the cities through the oscommerce admin panel, and allow users to seach for cities. I will provide the classifieds script. If you have any questions please contact me. Please only respond if you are very experience with oscommerce and php, and can complete the entire job. You must be willing to communicate through skype Thanks, Kenny