The first time when I have seen vegan omega 3 supplements, I have also been fooled into thinking that they are not much more expensive than fish oil, and I have bought some.
After reading the fine print, I have discovered that their content in essential fatty acids was significantly lower than that of products based on fish oil and also significantly lower than for an adequate daily intake.
This is a marketing trick to make their high price more palatable.
That is why in my previous post I have mentioned that the vegan supplements are 8 times more expensive per content of essential fatty acids, because their price per capsule is made to appear low.
The $4.80 per day is computed based on the recommended daily intakes for essential fatty acids, and not on the micro doses recommended by the manufacturers of omega-3 vegan supplements, in order to not scare their customers with the real high prices.
However, you may be right, because I have checked the current prices for vegan omega-3 supplements and the prices have fallen more than 3 times since the Q1 of 2021, when I have last checked them. So the price here would be only around $1.50 now, instead of $4.80 in Q1 2021.
It is indeed possible that where you live they are as cheap as you say.
Regarding liver, e.g. chicken liver, as containing concentrated toxins, that is a myth.
The liver is not a storage place for toxins. The liver is an organ that takes toxins from the blood that passes through it and then destroys them, typically by oxidation.
Immediately after a meal that happens to contain very high quantities of undesirable substances, there will be a time interval when the liver will indeed contain higher concentrations of those. For example after a heavy drinking, for some hours the liver will contain more alcohol, until it is oxidized.
However, after a long enough time since the last meal, the liver will contain less quantities of toxins than most other parts of the body, because they are destroyed soon after taking them from the blood, which other organs cannot do.
The domestic animals that are killed for meat are typically slaughtered after some fasting time, so a higher level of toxins in the liver than in other parts is unlikely.