This if falling back a bit to (my) general opinion area.
A MiniITX Ion platform should play everything. My main problem with the idea is that in spite of being MiniITX most of the systems recommended don't look much smaller than the MicroATX ones. Space is not a premium for me either but I'd like to play 1080p off of something minuscule, like the size of my wrist watch
With the arrival of MiniITX boards shouldn't this idea be more obvious? I don't quite see it. It should be a small box somewhere (small enough that you can hook it to the VESA mount on the back of your monitor - foreshadowing). 1080p/24, LPCM 7.1 out, done. It shouldn't be a premium. Connectivity to hook it to a NAS, either wired or wireless, IR receiver, wrap it. Premium models come with an SSD, the regular ones come with no SSD/HDD since you boot them off a flash stick - XP embedded, or Linux or in that general area. You travel? Should be small enough to fit in your backpack!
The only case that kind of looks like it is
this.
Sorry indeed, don't know a vendor in AUS. I hope you get something you like.