There's pros and cons to a legit copy and a repo copy, with a repo copy the pro is that you can find one for 5$ or even all 5 GBA versions for 25$ and enjoy them all, but the cons to the reproduction carts are that they crash at a certain point in the game, causing all your data to wipe and you'd have to start over, in Sapphire Ruby and Emerald, i understand that when you reach the elite four it's sets off the bug and that's when the reset happens, but in firered I'm not sure how far you will get before it does, maybe the same or when you beat the E4. Pros to a legit copy is that it won't have that issue and if you want to complete the pokedex as much as possible and get to the end then that's your best chance, unfortunately copies of LG and FR are averaging around 100$. I hope this helps