Maybe you should get screen protectors.

I know that some people on e-bay sell DSi screen replacements (I don't know how you would install it yourself, though :| )

But I don't think there is any cheaper way to repair it, unless there is a store nearby you that does system repairs that could possibly do it for cheaper. I'd just save myself some trouble and just pay the $25.

That is true it is there problem. You have a point there. They should replace your DSi screen...does your stylus have anything sharp at the tip of it (like a sharp plastic dot)?

I have encountered this problem with all of my DS systems (well there have only been 2 but still). I have found that they actually aren't scratches. If they were you would be able to see a brighter light from the screen under the touch one. Instead, they are just marks. Solution? Take a damp cloth and clean off the touchscreen. It should look good as new.

That's weird. Did you try putting your finger on the tip of the stylus?

I feel bad for you-your DS lite breaks and your DSi has a problem. lol.

Sorry to hear you're having this problem, but I'm glad to hear I'm not alone. Both styli that came with my DSi were scratching. I actually went through 7 styli and 3 screen protectors (all official Nintendo products) before I finally got one that doesn't scratch. Luckily the stylus never actually scratched my screen, just the screen protectors. Most of the DSi styli that I've seen seem to have a sharp bump that isn't really noticeable to the naked eye, but if you touch it you can feel that the texture isn't perfectly smooth. Strange thing is I've never had this happen with the 2 DS Lites that we own.

I know it's a little late now, but I would highly recommend getting screen protectors for any touch screen devices you buy in the future. A few dollars goes a long way when talking about preserving your investment.

They will not replace your screen for free.

I recommend putting on screen protectors that has a smooth surface. I have a pair of them on some of my DSs but I will not mention the names but hope you can find one

Im glad the stylus was faulty and was replaced for free. Not everyone will have the same case as yours but hope it will.

I bought protectors after my PokePark DS was scratched since Im not yet aware with the DS and the touchscreens but I learned very quick. My DS Lites, DSis and DSi XLs all have screen protectors SINCE I bought them

I don't know about dsi's but my ds lite screen protector came off just fine, it just made the corners a little dirty looking.

Nintendo's warranty is 12 months plus 3 months, if you register it on Club Nintendo.  You do not have to pay for the warranty.

I don't know if the warranty will cover scratches to the screen, but you should call them and find out.  You can call Nintendo at 1-800-255-3700 anytime between 6 AM and 7 PM Pacific Time.