[rartichoke]

It's not as simple as you think it is.

You mentioned wanting to allow farmers to make an account and add in their details of various stuff along with having their own profile.

That is much different than a typical e-commerce setup. Most product sites have products. Which account added the product doesn't matter. There's no "show me all shoes filtered by the user of Mary", it's "show me all shoes by price filtered by size, etc.".

I also encourage you to research shipping cost calculators that let you use them seamlessly in your custom site.

Also I'm not trying to discourage you from executing your idea. You're free to do whatever you want but I'm just saying you'll have to spend a decent amount of $ to get exactly what you want up and working as a reasonable solution.