I just ordered my Siggy lens that I have been lusting over for a week. The lowest price I could find anywhere was about $669 shipped both on eBay and from online stores.
I noticed that 47stphoto on eBay had a "Make Offer" deal setup on their auction listing so I put in an offer for $629 with free shipping and they accepted the offer in like 4 minutes. I was happy!
You might be able to get it even cheaper but I just wanted to let anyone know that's looking at getting this lens that you can get it brand new for less than the $669 advertised everwhere. Someone put in an offer for $599 and see if it goes through!
The difference that I saved was put towards a Hoya UV filter.