Make one. All you really need is a lump of wood and an old belt or piece of leather.
There's a decent enough thread on them here. It's effectively just leather glued to wood. Mine are anyway.
http://www.bladeforums.com/threads/m...-strop.640503/
If you don't have an old belt or leather scrap let me know, I have a box of off cuts and a couple of old belts; I'm sure I can sort you something out.