From my own research, the only issue with Cod Liver Oil is its Vitamin A content. Some people are more sensitive to high doses than others, but it is probably not an issue for most people. You are right, it is much cheaper than other types of fish oil or krill oil.
I'm not a mega dose fan.
I don't think any of us need to take as much as would cause Vit. A problems.
With Cod Liver Oil, a little goes a long way, and "that's a good thing"'.