These devices are typically very safe, because the video cards are what does the computation. Tampering with video cards are not very common. However, you still use it at your own risk. Want to be 100% safe? Buy it direct from the manufacturer. Even then, you aren't 100% safe, but they are more trustworthy than a random Listia user.
That said, nice auction, kas. I hope these naysayers don't get you down. I have been using Listia for a while. It is a nice site for the most part.