Actually, your DNA is not quite on sale. What is on sale is the ability to read your DNA through Y-DNA and mtDNA testing at Family Tree DNA.
I've written previously about the Tierney Clans Y-DNA project which is looking for Tierneys to participate in learning more about the surname's genetic history. If you've been waiting to check out your DNA (Tierney or not) now's as good a time as any. Check out the Tierney Clans Society DNA Project webpage or other surname project webpage of your choice and contact the group administrator for details on the limited-time reduced prices for DNA tests (offer expires August 31). Maybe you'll even find that your Irish ancestry includes a connection to Ireland's famous Niall of the Nine Hostages.
Note: I receive no financial cut from Family Tree DNA. Just trying to spread the word to those interested in tracing their roots.