Are Inferior Knock-Off ACD Spark Plugs Still Being Sold?

[Jet-X]

Getting ready to purchase new plugs (double platinum, ACD 41-962).  I noticed a number of deals on ebay that seem to be to good to be true.  A set of 8 plugs for around $24-30.  I recall years ago GM issued a bulletin to be aware of fake ACD parts, specifically spark plugs.  Is there a way to physically tell the difference between a genuine and a fake?  I though it had to do with either the metal color or the stamped markings.  I can't remember.  Can anyone recommend a known good source to purchase from?   Thanks  

[diyer2]

I would by them at a local auto parts store to avoid the fake ones.

Worth the cost tome.

AC Declo has a mail in rebate.

Google it.