Why am I having trouble finding a legit copy of Pokémon Emerald? [closed]

I have been looking all over the internet for a legit cartridge of Pokémon Emerald to gift to my little sister for her GBA SP. However, I am finding a LOT of fakes, through the looks, prices, and customer reviews. How do I find a legit copy when it seems the only ones on the market aren't anything but ROMs put on a GBA cartridge?

Unfortunately, legit copies of older Pokemon games are basically things of legend as of now. The prices may be very high for a real copy, but if the price is very low, then the cartridge is fake because the game is 5 generations old and people will charge very high prices for legit copies due to the game's rarity and age, and people will charge more money for older video games, but people may charge the right price, but forget things the cartridge art on a legit copy that make the fakes easy to identify.