I ran into the same situation with my prior '96 ES. Clumsy me accidentally snapped off the fuel lid door when taking out the gas pump after filling up at a station
As a temporary fix, I drilled out 2 holes on the broken door and used electrical wiring as hinges for the door. Later on I ended up buying myself a new door at the dealership (costed about $125 including paint). Unfortunately this is the only way I know of where to get that particular part for replacement, so best of luck.