Looking for directions for blog posts sorted by cities

Hi!

Ok, so I’m kinda at a loss here. I’m not sure where to go/what to do for this.

I want to create a blog (Or something) that basically is a “Category” site, kinda like a Wiki, where a single post could be re-used. And it’s mostly meant for sorting specific posts for my users.

The Post will be a particular item (Like Ketchup). There may be duplicates of this item, that belong in different categories.

Example:
Ketchup, in Categeory “Store 1”, in “City 1” in “Province 1”. (With a specific postal code, if I can implement postal code searching)
Ketchup (Same product technically, but different content, so new post), in Category “Store 2”, in “City 1” in “Province 1”.

so people can compare products kind of a thing.

Would I use nested Categories, and create a custom post type to help me with this? Anyone know of any postal code/zip code searching plugins for posts?

Help!!