Growing herbs to dry is not cost effective but...
I am not a full-on gardener. I don't even have the space for that, but I did grow a couple of herbs in flower pots this year.
I had to buy dirt, I had to buy the plants, and then a few months later they got picked, hung to dry for a couple weeks, and then I had to remove the leaves from the stems. In the end, I had like a half cup off one plant, and the others I didn't even bother collecting.
If you believe in a time=money economy, this doesn't add up, and you are better off buying from somewhere else.
A true economical model would mean getting trimmings from someone else's perennials, starting several plants, consistently watering, pruning at the right time to boost growth, fertilizing, harvesting multiple times a year, and wintering them so they last till next year.
You might get more for less money if you did it that way, but it takes time. Most people I know are not that time-rich.
I didn't buy them just to eat.
I bought them because on a summer morning, I want to step outside, drink my coffee, enjoy the flowers, and smell the thyme.
I bought them because I want to get a good whiff when stepping outside in the rain, so even if I have to run just to do something I hate it makes my day just a little bit better.
I bought them because if I can keep them alive, then even if I fail at actively doing anything else productive, I get to watch something I did grow into something better.
That matters more than a jar of herbs sitting in my cupboard.
(I also don't need three cups of each type of herb every single year.)
So, should you grow your own herbs? Sure, if you can find the value in growing things.
However, if it's just going to be another thing to add to your plate and leave you panicking, don't worry about it. Buy from your store, remind yourself that at least you season your food, and move on.