As of right now, there is no where to buy the studio version of Decoy. Decoy was the exclusive bonus track on the Hot Topic version of Riot!. As it was a Hot Topic exclusive track, it cannot be downloaded on iTunes, Amazon, etc.
A live version of Decoy is played on The Final Riot!, which can purchased in CD stores as well as digitally.
"Decoy" is about dating one person when you really like someone else.
Decoy
Skinit.com
It was a bonus track on the Hot Topic version of Riot!, so it came out the same day as the rest of the album: June 12, 2007.
You can buy Paramore hoodies from the Fueled By Ramen webstore or at Hot Topic.
You can buy they from eBay but if you want from a shop you visit i go to just music shops in the city or you can go to the official paramore site and buy it online.
Hot Topic
You can buy Paramore necklaces in their official webstore (http://store.paramore.net/) or sometimes at Hot Topic.
The song "Decoy" was a bonus track on the Hot Topic version of Riot!. A few different stores had exclusive bonus tracks for Riot!.The song can be downloaded on fansites, and they do play it live occasionally, including on The Final Riot! live CD/DVD.
You can buy them from the websites, Hot Topic and other music stores.
I live in Brisbane, and have the exact same problem. Sanity usually sells a couple of Paramore posters, and other than that, eBay is the best bet.
The plural of decoy is decoys.