Cheap Body Panels?

Nice project.
You will learn a lot of skills, both automotive-mechanical and personal discipline-budgetary through the process of rebuilding the car.
My best advice to you is be careful to not put the car ahead of everything else. Certainly make it dependable and safe, but don’t go crazy thinking you need to make it perfect.
Plan to drive it and enjoy it.
On your question about replacement panels, I have always heard that you get what you pay for, meaning that the cheaper panels may require more fitting time. And that would be important if you were paying a shop hourly rate, but if you are doing the work yourself it may not be that big of a deal.