Never again will I buy without escrow, even from respected members with extensive trade histories.
Sorry to hear about the bad luck but your making bad choice on no more group buys overall. Have had many good groups I've bought from. The one you bought from was on second batch, so that is in no means extensive trade histories.
Always keep in mind if it sounds to good to be true... it normally is. If major retail stores are having trouble keeping stock's of GPU's and someone comes along claiming to have access to lots of gpus and at super price.... should raise red flags.