It all depends where you live. If in the US most major cities will have juice/smoothie bars that offer fresh squeezed Wheatgrass Juice. You can also get in pill form in health food stores but I doubt it very much that the pills are anywhere near as effective as the fresh juice.
1.5 tsps of wheatgrass juice ain't much. Most juice bars sell it in 1 oz shots. Are you sure you didn't mean 1.5 oz intead of tsps?