I have used that lens and like it very much.
It has gotten good reviews.
The $590 price that shows on the Sigma site is the list price,
which is always much higher than the street price.
One of the most trusted cameras stores in New York is bhphotovideo.com
bhphotovideo.com shows a selling price of $389.
Amazon usually has very good prices.
There are several other prices shown in the Amazon ad.
Some are within $10 of the 47th Street price.
So it is not an unreasonably low price.
Resellerratings.com shows that 47th Street Photo has a lifetime rating of 9.21
But...for the last 6 months their rating has dropped to 7.29.
Since you are dealing with Amazon, you are probably OK.
Did you notice that Amazon says
"Processing takes an additional 3 to 4 days for orders from this seller."
My son just picked up a Canon 40D camera, Body only.
He is looking at buying a Sigma 17-70MM f2.8-4.5 DC Macro HSM lens.
He will be using it for Thanksgiving and Christmas this year and then getting something better with more zoom in the spring when he can afford more.
He found it on Amazon.com for $339.00. He said it ships from some place called 47th street photo.
I am a little sceptical about the whole thing because the Sigma site says it sells for $590.00
I have two questions. First is that Sigma lens any good?
Second. I have seen horror stories about dealing with some camera stores and the fact that is $251.00 cheaper than what Sigma is selling it for. The phrase "If it sounds too good to be true" comes into play here and I don,t want to see him get hosed.
Any advise would be much appreciated.