Use the link Tynstar provided. The scans in the link he listed should have the turntable box as the Front image, which is where you may be getting confused.
The stand-alone copies listed on Amazon are likely copies that were harvested for their turntables. I would be willing to bet those stand alone copies have no UPC because they were included in the turntable bundle.
Like Izret said, DJ Hero 2 was available as a standalone disc, but not DJ Hero 1.
If you guys say so. Some one should really get an image of the box if thats the case.
Heres the UPC for the game inside the bundle: 047875961944
They all have a sticker over the case UPC which is likely because it is an orphaned bundeled unit like you say.
Anyways, sounds like a losing battle here.