American Metals
740 West Broadway Road
Mesa, AZ 85210
(480) 834-1923
Also try
Space Age Auto paint
707 South Country Club Drive in Mesa, (480) 835-0971
Open Weekdays 8am-8pm; Weekends 9am-5pm
They have some bar stock and angle iron.
Lots of paint and body supplies.
They can custom blend paint to match factory colors
and either put it in a can for you to use in a spray gun or
put it in a rattle-can for ya.