If your hunting for Perfects its more efficient just to go hunting for one, but best way to make money quick is to have a team of 6 armado using the hoarder trait to pick up items after battle. Escape flashes sell at 2000 a piece so it'll take 2000 of those alone, but you can also sell off the extra spinners cakes and scents they pick up to. It never gives you the option to use the Coupons, so no on that one.