Of the 12 lenses that I've owned and sold, or currently own, I've only bought 2 new. One was a FA35/2.0 that I got in Hong Kong, and the other one, the Sigma 50mm F1.4 EX DG HSM was bought from DigiDirect's Sydney store, near the QVB. I usually use B&H/Adorama and
Shopbot to judge how much I should be paying for lenses, and usually it's cheaper from overseas, even factoring in shipping. But, in the case of the Sigma 50mm F1.4, DigiDirect had it for A$556 and the lens is local stock with local 12mths warranty from CRK and I could try it in store first before buying it, whereas buying from B&H would be ~A$590 lens only, and then you have to factor in the shipping as well.
In the future, if I were to buy a new lens, I would take a look at B&H/Adorama's prices and see if I can get CRK to price match or do a deal.