It depends.
Our original CSA, we had for 15 years. It ran $19-25 a week. It was local and organic. I ran the numbers a few times, and it was a few dollars a week cheaper than if I'd bought the same (non-organic) groceries at the grocery store. That CSA shut down due to the drought, but they recently started up again.
After they shut down, I switched to a similar service. We have a few CSAs in town, but now we have 4-5 produce delivery services. These work LIKE a farm CSA except they pull from multiple farms. Thus, you get a little more variety.
One of our services (we get two, we spend about $66-70 a week on the two), gives you 11 items a week, and each week there are a list of 4-5 other items that you can swap out. So, there is SOME choice. Occasionally on the actual day, something isn't available, and they substitute (like getting fennel instead of radishes). The other service, there are no subs.
It's not a complete surprise, they tell you what you are getting ahead of time. Both have add ons, meaning if you really want carrots this week but aren't getting carrots, you can pay for carrots. Both allow you to skip a week. If you look and see a bunch of chard and spinach and think "no way", you can skip it.
It's been almost 20 years for me now (started in early 2001). I find that I have much more ability to cook different things. That's good!
Also, the food is far fresher. The heads of lettuce from a local farm can last up to 2 weeks in the fridge.
The food tastes far better.
I support local farms. What do I want to see in the world, and in my county? I want farms. I want to be able to buy from the farmer. If I don't buy the stuff, then they will all go away.
The other positive, during COVID, is less shopping. Both of my services almost immediately got swamped and had to cap off their new customers. The others in town also.
Also: no plastic.