Amazon has cheap ones. I just bashed the bottom of the one I bought closed so the flagpole doesn't slide through. Used a 1" wooden dowel as the flagpole. Before that, I just zip tied the flagpole to the spare tire between the tire and tailgate.
For local Jeepers in the DMV area to meet up for trail rides, muddin, sell new/used parts, group buys, photo shoots, etc.. NOVA JEEP's official Jeep shop sponsors include: Bull Run 4x4, Inc....