YOu poor thing...this heat has been terrible in sydney of late - dont know how your surviving without a/c.
Dont know much about portable air cons...melbels idea sounds like a good one though. Another way to keep the room a bit cooler - you have to stop the sun frm hitting the bedroom window...how do youd o that ?? have you seen those cloth awnings - they wind out and in ? have you got heavy duty curtains on the windows ?? it may all sound silly, but our bedroom gets arvo sun. We got a awning thing erected about 6 years ago, and i made some really heavy duty curtains....it defn makes a difference.

Maybe worth getting a air con person out to give you some ideas...wouldnt hurt to get a price..???