You can still get them from Toyota apparently, however, they will want to check out the car first to ensure that its a genuine GrpA... otherwise I'm sure that you can get them aftermarket somewhere out there...
The Group A specific stickers are: right hand side of boot there is a Group A Rallye sticker... on the bonnet vent/scoop there is a Water to Air Intercooler sticker, on the doors at the front there is a 4WD Turbo sticker and at the back there is another two Group A Rallye stickers...