Yes they also had a 170-500mm in the window. They normally sell for £500.
The price was about £750 and it looked very much like the 50-500mm.
I was very tempted to go in and try it out until I noticed it was a Nikon fit.
Checking the Sigma website the 150-500mm looks a bit different so I think they must of written out the label incorrectly. I did look at the label twice because I thought it was a 50-500mm.
Sorry to get you excited for no reason.