I have plenty of used base model 99-04 Mustang bumpers. MIGHT even be able to get a similar or same color. $150 for the cover and foam if you need it, $200 for the cover, foam and rebar if needed.
Front covers...no used...I can get you a new one for $125+tax. Just need a deposit to order it. They come in black primer and just need to be scuffed and painted.