Saw this at Liverpool Officeworks, don't know if it is at other stores. There was a clearance tag saying $49.95 on the shelf however on the system it was $79.95. I had to take the tag to the counter. Maybe you can use the receipt to price match if its not the same price at your local store.
There were around 10 left at Liverpool when I was there.
Are these 5400RPM SATA drives? Are they easy to take apart? :P (Being cheap and saving $10 for PS3 HDD replacement)