As everyone has said, you can save alot by purchasing your fish oil supplements elsewhere.
For example, see this:
Amazon.com: Grizzly Salmon Oil All-Natural Dog...
I, personally, feed the real deal instead of supplementing. So I will feed canned sardines in water (lowest sodium content that I can find) weekly. For a kibble-fed dog, you can just add a teaspoon / tablespoon (depending upon weight of dog) to their food daily. Either, or a combo of both, will work and will save money.