Vanbar have one of the worst online shops in the hemisphere, in my humble opinion. But! they do have it listed, under an entirely dumb name, "Ilford MGRCP 10.0x15.0 100sh portfolio", Ref No: i252-100 - no mention of it's postcard nature at all, but that's the one, $40.08.
If you email them (orders@vanbar.com.au) they should be able to tell you if they have it in stock. They also let you pay via direct deposit, which was always handy for me when I was starting out - but keep in mind their postage expense is almost always $20, no matter how small an object you're buying.
I did purchase a box from them about 2 years ago, but when I tried to order some stuff from them back in January, it took them a month to call me back, so I'm a bit iffy about them now. I was gonna go to Total Photographics and try to beg them to order some in for me...