My wife does some work for the Salvos and apparently a One Planet McMillan was just donated.
She says it's in good condition. From the way she explained it to me over the phone, it is a reasonably recent model (ie, with the straps connecting the back of the lid to the pack, rather than the solid canvas panel that the older models had). Not very recent, obviously, as they no longer make the McMillan.
Size Medium.
$150 is a mega-bargain for this pack, which is worth around $600 brand new, I think. If you need a large, tough, canvas pack, these are hard to beat.
Salvos shop, Legana (Tasmania - 15 minutes north of Launceston).