Evidently phone chargers are not good to use with a Nintendo DS Lite, as they're liable to damage the system. What about a GameStop Switching Power Supply?
Searching the Internet, most hits for those kinds of search terms lead to auctions and used sales, not good, firm descriptions of exactly what it's good for. I believe I remember using one consistently a few years ago to power my DS Lite at the time, and it does appear to charge them, but is it safe? Here are a couple of photos, in case they're needed: