The Official release of the Tizen based Samsung Gear S might only be a matter of weeks away now, as we expect an October release date, but that hasn't stopped it going onsale already.
The website online retailer Aliexpress, which is a online retail service by the Alibaba Group, has put the Gear S onsale and titled as "Samsung Gear S SIM watch phone pre sale". The current price is $385.87 USD with a shipping of $14.06 to the UK, with estimated delivery time: 5-10 days (ships out within 30 business days).
The seller is Shenzhen All-Rich Trading Co. Ltd, and seems to have a reasonable reputation on Aliexpress, but refunds are only accepted if the item is not as described, and does not cover things like it does not fit properly. I don't actually know either aliexpress or Shenzhen All-Rich Trading Co Ltd, so its always good to be careful.