Here's my experience making my own parts...
I wanted to design and make my own stuff for quite some time, finally came across a nice deal on a lathe and mill in good shape so I bought them and got them down the basement and running. That first week all I could tell anyone I knew was that I'd never buy another part that I could make myself.
Three months later after learning just how much skill it takes to even make two simple parts identical to each other, plus all the time sharpening/replacing tooling, learning how to setup a job properly, learning proper feeds/speeds, etc, etc, etc, I pretty much covered the machines up and haven't used them since.
Now all I tell anyone is "I'll NEVER make a part if I can just go out and buy it"
Your mileage, of course, may vary...