It appears the one Doc Oz had on the show was from here:
PURE HEALTH - Green Coffee Bean, Pure Raspberry and Superfruit Juices
At 800mg a day, this brand would cost about $26 a month. {edited...wait...their brand says 400mg, but it takes 2 pills to make 800mg, so I guess you'd need to take 4 pills a day; which means about 4 bottles a month, right? So it'd be closer to $52 a month. Am I doing it right? Lol)
Interesting.
Another supplement that has studies behind it is EGCg, which is part of Green Tea extract. You do have to buy 'standardized' EGCg...not just "green tea capsules" etc.. info:
Green Tea-Obesity Studies
This is the one I get, which has the right EGCg stuff:
Amazon.com: NOW Foods EGCg, Green Tea Extract,...