Develop an Add On for a Classifieds Script

I'm looking for someone to develop an Addon for Geo Core Classifieds Software (http://geodesicsolutions.com/geocore-software.html). This Addon will enable a user to list their item in multiple categories. During the listing process, the user will be asked a number of questions about their item. Based on their answers, their item will be entered into the relevant multiple categories.

If a user has their item listed in more than one category, they should still be able to take advantage of the same benefits they would have if they had 2 separate listings e.g. Choosing to be Featured in category 'A' and/or 'B', pay to move their item to the top of the results for Category A and/or B, etc.

The Addon must adhere to the following guidelines http://geodesicsolutions.com/support/geocore-wiki/doku.php/id,developers;addons;start/#geoaddonscom_guidelines . I need someone who is experienced in programming, if this is not economical I am willing to look at alternative methods.