Properties of Javelin Quiver?

One of my players wishes to carry javelins. It seems logical that these could be carried in a quiver (appropriately sized of course) that would reside on the wearer’s back and would serve a similar function as a quiver does for arrows.

We cannot find any reference material for such a thing (how much it would cost, how many javelins it would hold). Is there a place where such a thing is specified?