Our Research on Goji berries suggests:

Goji berries, Zhongning County
Ningxia, China
Goji (Lycium barbarum) is known for bringing the body from acid to akaline in a short time. It has helped people with Crohns disease, acne, arthritis, acid reflux, headaches, kidney problems among many others.
Many people in the regions where goji berries are grown and eaten are to a large proportion free of arthritis, diabetes, obesity, cancer, and many other diseases.
Studies in Asia, Switzerland and the US have found that Lycium barbarum contains some unique polysaccharides. These have been isolated from the berries and were used in several experiments. The unique polysaccharides have been shown to improve resistance to cancer and to have very promising anti-aging properties.
Goji berries are used in traditional Chinese, Korean, Japanese and Tibetan medicine. Mainly for their action on the liver, lungs, and kidneys and their ability to enrich the yin.
The names "Himalayan Goji berry" and "Tibetan Goji berry" are probably a myth, since there are no objective economic, scientific, or government reports on the commercial production of Lycium berry species from these regions. Moreover the climate and soil in a large part of these regions would not allow such cultivation. The said goji berries are probably grown in Inner Mongolia, Ningxia, and western Xinjiang, China. But the word "Himalayan" may sound more appealing!
There are two very closely related species known under the latin names Lycium barbarum and Lycium chinense. The Lycium barbarum is the one with more vitamins, minerals and antioxydants. Common names are Chinese wolfberry, goji berry, barbary matrimony vine, bocksdorn, Duke of Argyll's tea tree, matrimony vine. "Tibetan goji" being a specific species, given variously as Lycium eleganus, Lycium eleagnus, Lycium eleganus barbarum is probably another myth. No such species exist!
Goji Juice products are mostly containing several other berry and fruit juices, but are nevertheless labeled as "goji juice". The percentage of wolfberry contained in these juices is generally not stated on the product labels.
Verdict:
Most Goji juices are mixed with an unknown amount of other berries and are nevertheless very expensive. If you care about pure products, your choice is Goji capsules equivalent to 1500 mg of whole fruit.