Think of growing a yard this way: mostly gravel (and no sprinklers) but instead wide-spreading plants that can have water efficient water-dripper systems installed.
Vertical Succulent Garden by floragrubb: 20 x 20" panels with 45 slanted cells to support planats and soil when mounted vertically. The unit in the picture is made of 6 panels, each $79. Now, if I could only figure out how to make the panels myself..