I started with the promarker route plus photoshop as i wanted to see if i could do them quick. 20 mins for the basic, then another hour for the rest (more about experimenting). If i follow that style it could be quick it depends on whether its too scrappy.
Promarker, and .3 and .5 felt pens.
Various, cutout plus poster plus gold style with some colour burn (grr tiger).
Black and white option, pencil, and 2 layers of black/grey.