If you consume "algal" oil of 50 cents per day, that must be some kind of capsule with a small amount of oil, e.g. a few hundred mg of DHA+EPA.

This is much better than nothing, but it is far from a daily intake comparable to that of the populations who live in places with access to cheap sea fish, where such fish are a significant fraction of their food (e.g. Japan).

If your target is to match the diet of such populations, that means e.g. 5 mL per day of non-diluted "algal" oil, i.e. a teaspoon of such oil (or 10 mL of fish oil), which contains around 2 grams of long-chain omega-3 fatty acids.

That would be much more expensive when using "algal" oil, at least judging after the prices seen e.g. on Amazon.

In order to not scare the customers, many sources of "algal" oil have a similar price with fish oil, but only because they contain much less omega-3 fatty acids per capsule. If you read the fine print, then you discover the true price ratio.