Personally, I use canned fish from the supermarket when I cannot get good deals on fresh fish -I get Jack Mackerel - Salmon & Sardines in Spring Water. I use it a few times a week....dogs LOVE it. I also use Sockeye Salmon oil on the days I do not feed fish <1000 mg per 30 lb>
If we are talking about omega fatty acids, you can feed just plain old canned fish like Kathy said above...its probably cheaper than Evangers. Just giving fish oil capsules that are for "humans" is actually a good way to supplement omegas into their diet. We give our girls 2-3 of them daily as treats and they love them...much cheaper to buy them in bulk than to buy canned fish.
Also, grass fed beef or game meat is very high in omega fatty acids. So if you feed grass fed beef or game meat once a week your omega bases should be covered.