I'd love one too. I don't think they've ever been released for general sale though, kind of like a baggy green deal. My primary school had the exact same design as our SAPSASA guernsey, minus the SANFL logos and all that of course. Should've flogged an XL one.
I managed to grab one a few years back before a SANFL state game, and it is still in my wardrobe and no it isn't for sale!




