Assuming you are not using a DStwo/issm/iplayer then it is not a GBA emulator but actual GBA hardware.
Anyway I am seeing DSes and DS lites go for next to nothing at yard/garage sales and similar, not always but often enough. Equally if you have a bit of cash to splash around then people often bundle a DS with a bunch of games (typically craigslist and local facebook selling groups) and let it go for far less than it might go for individually so buy it and flip the games if you want. Amazon and ebay prices for screen replacements (no idea as to the quality, or indeed even if it is like some phone screens where you get third party nastiness) seem to start at around $6 if you are lucky and I have seen them go for that. Equally you don't have to be the most selective in your purchase -- you presumably have a working battery there, and possibly some other parts if you want to mix and match parts.
That said the screen could be a ribbon slipping fault (take it out and put it back in), a connector fault (various fixes, most of which are no fun) or an actual screen fault (for non TV/pricey items I tend to suggest just straight replacement). You can try taking the connector off just by removing the back case though so might as well try that first.