One of my first jobs after computer technician school was working as an Apple, Dell, and Compaq tech so it was easy to get any Apple parts. But without the license, it's hard to just have Apple parts shipped to you in 24 hours. I don't know how easy it would be. We all know that getting PC parts is far easier overall.
What you are attempting is more advanced and not as easy as working with your typical PC tower and easily interchangeable parts. It's not impossible, but not easy. Take time to research your project.