Interesting. I'm building an arcade cabinet right now. I have some limited skills working with wood, but by no means am I carpenter. I debated buying a kit, but could not find one that I was happy with. So I'm building from scratch.
I have been proceeding very slowly and teaching myself new skills everytime there is something I want to do, but have not done before. I am *very* happy with the results, and there is absolutely no question that I value this piece of work far more than if I had just purchased it. In fact, I've estimated that considering the time and labor I've put into it, I would need to sell it at at least $10,000 to break even. This is far more than I think anyone would be willing to spend; but it is what I think it is "worth".
On the other hand, this cabinet is highly customized. And perhaps this is the the more practical reason why I value it so highly. It's true that I wouldn't pay $10,000 for a "stock" arcade cabinet like the one I built. But if I had gone to a master woodworker and stood over his shoulder directing him to do all of the major and minor tweaks that I did, ask him--mid stream--to throw away assemblies he had done and re-do them in a different way (because I changed my mind after seeing what it looked like), and to have him overbuild and overfinish it in ways users would never see or appreciate; yeah, I guess I wouldn't be surprised if he charged me at least $10,000.
So yes, I think we tend to value things we produce ourselves more highly than those built by others. However, for me in particular, when I really think about it, the reason is less about self-love than it is about customization--and even small customization can have tremendous value if that's the thing that you *need* to make the thing "perfect" for you. The thing I like so much about Open Source is that I can go into it and make those little tweaks that make the software do exactly what I want. A good example of this is Atari800, one of the emulators that I use in the cabinet. I really like this emulator, but it had some annoying (to me) minor issues that made it less than perfect for my application of it. So I contributed fixes for these things to the project. So now my project is perfect. And I value that a lot.