How should I divide up my project into applications?

I am using Django to create a small website and a small store to go along. I was wondering what are good conventions to split up my project, how do I decide I should create applications with more specific functionality.

I heard alot of people write about either projects with 80(!?) apps or tell me each app should have it's own designated and independant functionality. The first makes me none the wiser and the latter indicates that I should create a single app for the entire store. Since payments would be useless without products, and without a shopping cart why even bother with payments...

Before I started looking into how I should split it up I guessed that I should divide my shop in something along the lines of: Orders, Profiles, Products and Payments. Where an order is a collection of products, a profile and a payment. Where the payment can be uninitiated, in progress or completed. I believe this would be everything I need for a store.

Do any of you have any advice on my implementation or any concrete suggestions on dividing a project into apps, espcecially when on a smaller and simpeler scale. Any articles or resources would be much appreciated!