The main feature that the script should have are
1. Search Autosuggest
2. Customizable fields for categories
3. Geo-IP (It should take a person to their respective cities if available or should take them to the homepage)
4.Multi City domain feature(ie city.xyzclassified.com)
5.Other features similar to oxyclassifed script
Note: Please check quikr.com for the functionality and form design (Post a classified form, select a city from a drop down menu and other similar functionality etc). The person can use oxyclassified also for this purpose as it has most of the features. But please make sure that the soultion should not resemble to oxyclassified script in looks.
If you already have a ready made solution, please send a demo link.
Please see the attached dociment for more clarity.