Actually, pretty much any type of high end audio gear is prone to scamming. However, if you know what to look out for then you are pretty safe.
1. Don't buy from anyone in Indonesia or Turkey, etc, etc.
2. Check the images to see if you can spot any anomolies. For example - a Mackie D8B mixer should have a distinct looking CPU unit - many auctions I've seen show a standard Dell PC in place of the propriotry CPU. What idiots!
3. Ask loads of questions and see if you can trip them up.
