You can easily make your own with a canvas, a paint brush, masking tape, and three colors + white acrylic paint. Just tape up your canvas every which way, paint a gradient of each color in the taped segments and remove the tape
DIY Canvas Painting - Canvas paintings are the easiest and cheapest way to fill a wall with art! They can be as simple or complex as you and your painting talent want it to be. Anyone can do a simple solid canvas, or add stripes, shapes, simple designs.