The Mac and PC version for Adobe Photoshop CS is around S$1800/- (max price). Educational version for both platforms are at S$800/- (max price) THe Adobe Creative Suite Premium CS is S$2200/- (max price).
There is a download option from Adobe, which means that you can get it at US price of US$649 and save some shipping cost. Read the terms and conditions to make sure you qualify for the download purchase though.
I only have Photoshop Elements 2, and if I'm not wrong, it lacks many features found in Photoshop 7. Of course, it can be as good as PS7 if you know the workaround. The extra features in PS7 probably means you take less clicks to get the job done.