Toyota part number is #53801-2B080 (RH Fender)and is discontinued (at least in the USA).
Last known retail price for the above fender was $258.11.
They list a fender for the std coupe and liftback. Still available. #53801-20840 Retail $302.20 6 shown to exist in the USA.
And they also list a fender for the conv. Discontinued....
Without modifying a standard Celica fender, you are looking for a 1988 or 1989 Alltrac only fender. There seems to always be somebody parting an ST165 out on the boards. Just remember that the cladding that Toyota added on those fenders can hide a lot of sins...namely rust. You may be better off to have the seller show you the fender without the trim on it or modify a standard fender.
Good luck.