I've seen lots of DS Lite and DSi parts on eBay.

Has anyone built an entire DS from parts before?

I'm thinking about building a DSi, or should I just buy the GP2X Caanoo?

Building a DS/DSi is a completely crazy idea.
If you buy parts separately, it's likely that some will be broken, and it's also likely that you will break something. The DS parts are *extremely* delicate, way more delicate than you'd expect.

Last summer, I broke the hinge of my DS lite, and bought a replacement case to fix it. Even though I was really really careful, I broke the top screen ribbon cable. Any single scratch will make it stop work. I had to buy another

So my advice: don't try to build a DS. Anyways, what'd be the point of it? You can't customize it like you can when building a computer. You'd get the same thing than when just buying a DSi.

I know how delicate DS parts are. I've disassembled the bottom half of a DS Lite before to fix the R shoulder button on the motherboard. I had to disconnect a couple ribbon cables, and take the whole motherboard out from the bottom casing, leaving one ribbon cable connecting the motherboard to the top half of the DS. I had to buy new shoulder buttons, and a tri-wing screw driver from eBay.
Here's the toughest part:
Those shoulder buttons are tiny, maybe a tiny bit smaller than a bracket for braces. My dad de-soldered the button on the motherboard, and soldered in a brand new shoulder button, with a hand held high quality soldering iron. We didn't even use a magnifying glass. And when I re-assembled the DS by myself completely, every feature on the DS worked flawlessly. Except the R shoulder button now has a funny click to it.

I realized later browsing through eBay, that it would have been much easier to just buy another motherboard for about $5.00

Dirbaio: You got a point, you can't really customize the DS much at all. Other than assembling a cool transparent casing on to it, or assemble a DS with your own mini speakers. But it does cost less, than buying a assembled one in a box. And, I think building your own stuff is kinda cool.

Wow, so you were lucky to have no problems at all when repairing the R button. Congratulations

And I didn't know it costed less. I'm surprised: It seemed reasonable to me that it would cost more.

Cost more? Interesting.

I've learned that buying anything assembled will cost more than buying the parts. Because, the assembled piece includes the time and effort to build it + the cost of the raw parts. And the raw parts are just raw parts. So because the assembled piece requires more than raw parts, the assembled piece will cost more. If you get the raw parts, the time and effort to build the product goes onto you.

Well, I know nothing, and I haven't checked the prices, so I'm just guessing.
It seemed reasonable to me that while you could buy a complete DS at the shop by your home, finding spare parts is more complicated, and you usually have to pay for shipping, so the costs of the separate parts would be higher.

But, you can always buy a used DS. If you want it cheap and easy, that's the way to go.

All well, at least my question is answered: no one seems to have built a DS from scratch.