I have seen them in Daisos (where I am now, there is only a small Daiso), but sometimes the hardware store has them---you can get the kind with two or three steps on them, that slide together and apart to fit the space, or you can just use a piece of wood (or two) or inexpensive empty square plastic boxes to lift things up. Sometimes Daiso has kind of flatter plastic boxes, actually trays used in drawers, that can be flipped to make a riser, but ideally you don't want the riser to be two cans deep unless you are "queuing" the cans on it.

If you stack a couple of cut-to-size 2x4s and glue them together, that works well too and the width is about the same as most cans. You can cover it with contact paper for a smoother look. Works only if you have a hardware store do the cutting for you.

The wire racks are too rickety in my experience.