I've been doing extensive research since watching the infomercial this morning on television.
What I've discovered is that if you have a Latin Grocery, specifically Mexican, you might be able to buy the same product, in original form, called the Nopal "Tuna" or Prickly Pear.
As shown in the infomercial, it's the bulbous fruit in usually reddish purple color that grows on the green cactus "pad" or paddle. I will be going to several Latin Groceries here in the Las Vegas, NV, area to both see if I can find it, and if so, the cost. I will also do further research to see if the Green Nopalitas (pads) will be an adequate substitute.
If I find the pears and price them, I'm sure a juicing machine will be able to produce enough home-made "nopalea" at a fraction of the cost, most likely enough to get the juicing machine to pay for itself.
I'm 100% sure the substance itself is not a scam, numerous clinical research papers have documented the benefits of Nopal fruits. However, TriVita is still an MLM venture, so I would be bane to be extremely careful in dealing with them