Chinese Wolfberries (Lycium barbarum) Won't Fruit

I purchased Chinese Wolfberry seeds 3 seasons ago from Richters. After starting the seeds in the greenhouse I transplanted some to the garden (Zone 8) Some remained in the greenhouse. The transplants were located in different soil,sun/shade, drainage conditions. All seemed to thrive and many are around 6 feet tall. I experimented with pruning/not pruning. None have borne fruit! Am I too impatient? Can you suggest anything that will encourage fruiting?

You are doing the right thing. Commercial growers prune their shrubs two to three times a year to get well-branched shrubs that keep the resulting berries within reach and to get heavier fruiting.
Many trees that are grown from seed need to get to a certain age before they will fruit. Once the tree is mature, any cuttings made from the mature tree will also carry the "maturity signature" and will fruit even when very young. This is one of the tricks of grafting: amature bud or scion is grafted onto an immature understock and the resulting branch will fruit very soon. I could not find any reference in the literature to how many years Lycium barbarum takes to mature, but most shrubs take about 4 to 6 years and trees take two to three times as long. You should see the first flowers in a year or two.
Keep in mind that Chinese wolfberries like well-drained, alkaline and moist soil and they need full sun to fruit properly.