How to grow an endless supply of Basil without buying seeds again

Basil seeds are pretty cheap, they're only 75 pesos for a packet containing... a lot of seeds. (You think I'd count them? hahaha)
So, why would you bother saving seeds when you can just buy them right?
Well, if you're an extreme cheapskate then there is no need for an explanation why.
If you're practical, like me.  I would say why not?
Why would you buy something that you already have?
It only requires little work and you get an endless supply of seeds and plants for free!

The seeds come from the tiny flowers, each flower contains four seeds on average.  Imagine how many seeds you'll end up with with just a single plant!
You can't use up all of it, but you can always give them away to friends, which I plan to do in an effort to encourage them to start growing their own food as well.

Let's go back to the process of seed saving.
You can either cut off the stalk with the flowers and then let it dry, or just leave the plant alone until it dries up/dies.

Smells really good!

You see those black stuff? Those are the seeds.
Each tiny flower contains four of them.
It was very time consuming picking them out gracefully.
The best way is to just shake it and crush them lightly for the seeds to come out, then you can just sift it later to get rid of unwanted debris.

That is pretty much all you need to do.
Keep the seeds in an envelope, label it (name and month when you saved the seeds) and you have tons of seeds to replant, giveaway or sell if you want.