oh HGtv, they use this product a lot on the show income property, to sound proof the basement rental unit from the rest of the house.

http://www.soundproofcow.com/soundproofing-insulation/soundproof-insulation-batt.html

Holmes on homes, used a sound proof drywall on a townhouse with sound issues between the common wall.

Here is the product that he used.
http://www.quietrock.com/


i can not speak to value of these products, but i would assume they are quality products if homes, and some of the other guys on HGTV like them... Good luck, maybe someone else will be more knowledgeable than myself on this subject.