The easiest way to make sure that the tickets you are buying on halfvalue are legit is to follow some very basic steps, much like you would if you were purchasing the tickets from any other vendor.
1. Make sure the seller is reputable. Good feedback is always a plus.
2. Pictures of actual help. If they exist, it helps to be able to see them. Not always necessary, but makes you feel better.
3. Buy through halfvalue. Protection from scams - to some degree.
4. No what the tickets SHOULD cost. If you are getting a great deal - to good to be true - it probably it not real. Check around other sources to make sure you are getting the proper price.
5. Ask questions. Any good seller should easily be able to answer an question you have about the tickets. If they can't - run away.
6. Read the listing carefully. Make sure you are bidding on what you think you are bidding on. Some listing are confusing - not even intentionally. Read carefully.
7. If you are uncomfortable, watch the item and see what it sells for; then you can be more confident the next time those tickets come up.