Home improvement store.
Get the thinnest plumbing pipe you can find and a right angle fighting. Usually 3/4 ". Since it comes in different lengths its easy to customize.
For the base end use pipe fitting ceiling brackets and scrap piece of wood. Usually this is behind your tank or stand so it doesn't have to be pretty . Spray paint it white or black.
Securing the unit to your ad hoc L bracket requires some creativity. You can build a frame with wood and put the light in the frame and suspend the frame, or secure it tightly with string or wire. Friend of mine hung his lights with black aluminum wire so the look like they are suspended in air.