I have a section of cut down aluminium crutch that serves a similar purpose, albeit usually for the front of the bike (although it works on swingarms in this way for bikes without centrestands). Fabrication/modification took me about an hour. Refurbished single crutch (enough to make two) cost me about £10 delivered on ebay.
It works well enough that until I got my hydraulic jack, it used to be the main way I'd jack up a bike, even when in the garage.