Here is the truth and nothing but the truth and all the facts that count.
You CAN buy all the parts you need from Dealsextreme, I just did.
You require the Nintendo screwdrivers by the way, nothing happens without them.
You need to search Youtube till you find a video on taking a DS Lite apart. They are easy to find. Keep watching them till you find one where the guy speaks clearly and can actually film the process and in bloody clear focus. Remember, you need to SEE what the person is doing. Just because THEY know, doesn't mean you will see what he is doing.
It is easy to take a DS Lite apart, but only if you can see the steps properly. It's not really all that hard unless you are all thumbs have no decent lighting and refuse to accept you need a decent Philips screw driver as well as a sharp hobby knife as well as a magnifying glass (trust me you will want to look in close at some things).
The cost of the parts is nothing (unless you are yet another whiny teenager that thinks 5 bucks is a sum of cash worth mention).
There was only ONE part of the process I hated. The small insignificant teeny cable that comes from the bottom screen from underneath and connects to the motherboard is so friggin finicky to attach, it may well make you decide that a new used DS Lite on a site like Kijjijji (I can never spell that site correctly) or craigslist or something is a better idea.
Otherwise the repair process is not too hard.
I had to fix a broken housing part, a portion of the lid hinge that houses the metal pin that basically holds the lid at whatever angle you have it opened to. So I bought a new DS case set, and most of the parts were redundant. It took me a chunk of afternoon, but I am also a veteran modeler and this sort of work was nothing to me (even though I hardly knew what I was doing).
And yes I fixed the DS Lite. I don't use it though, it's my son's, but I told him if I fixed his defacto garbaged DS Lite, I owned it
I loan it to him now.
In retrospect though, I don't think I would volunteer to do this again. So be warned, it is not complicated but it takes a few hours on the first try.