Would it make more sense to use a framework to build an commerce site, or build it from the ground up?

Question

Keep in mind, I know PHP as I learned it for this specific project. Also, I thought about just using magento, but as I went through it, I realized I would have to learn their framework. I am very opposed to putting more time into learning a framework rather than continue expanding my PHP knowledge. I took a computer science course in which rather than make us use already made objects and functions, we had to create those as to learn how they actually worked. That was an amazing learning experience. I know that their is a lot of work involved in doing this, due mainly to the fact that others have done similar things, but my main two reasons for this are:

1. I would only build what I need, no extra features I do not.
2. I would have specific needs, stuff that I would need to code anyways.

The only thing I would need would be simple e-commerce features like user authentication, products pages(user, admin), and shopping cart, and obviously a database. Everything else I need would be tailored to the specific needs of the site and the way I will be implementing it. If this helps in giving a picture of where I am at, what would the best recommendation be from professionals. Thank you.