That happened to me a while back on eBay too.
I found a Koni Omega step with a BIN, it had only been listed for 20 minutes.
I bought it and paid for it as it was a very good deal.
Then the seller cancelled the sale and refunded my money telling me he sold to a camera shop instead.
Sure he sold it to a camera shop after listing it 20 minutes beforehand!

In better deals I did get a quite nice 2.8C just like the one in this post from a local via CL for $120.