the $700+ one should be the sigma 18-50 f/2.8 (constant aperture)
i don't really get you, just because the shop sold the lens to you for $6 less than what you get in singapore (which is still cheaper by the way), you feel like you've been cheated?
what is the official price in shanghai - shouldn't you be comparing to THAT, instead of aiming for $300 savings and being unhappy when:
1) you can mix up 2 lenses, thereby identifying you to be a easy carrot head asking to be chopped (and thus, the UV filter is self-explanatory)
2) you still save $6, it's not as if they charge you $800 for a $400 lens
3) you didn't do your homework
i'm sorry, but you get no sympathy from me.
please do your homework next time, and be clear on what lens is what lens. next time you will go buying a 70-300 f/4-5.6 cheap lens (costs $300 thereabouts) for $400 and be very happy thinking that you purchased the 70-200 f/2.8 (which costs a lot more). caveat emptor - especially when buying overseas.
To purchase a lens was a last min decision because I have quite alot of spare rmb.. I am definate on the lens which is not the constant aperture model..
It was a holiday last fri so I tried to ask my bro to check on the prices instead of calling myself because the idd charges are quite expensive.. To get an internet access in china ain't easy as well, cannot even rent a computer at the internet bar for foreign passport holders.. That was the last day I can get the lens there because we are on a group schedule, either I get it or missed it..
So the bottom line is trust yourself and check everything in advance..