Though the equipment costs are higher to get into All Grain brewing, the grain cost per batch will be considerably less than buying extract. You also have more control over the process with all grain, more creativity, and the potential for a much better brew. If you continue on with your brewing, the lower batch costs will gradually pay for the additional equipment costs. ....unless you are like many of us here that are always looking for something else to buy for our "Breweries."
None of us do this strictly to make a less expensive beer, though you can not buy beer of home-brew quality off the shelf at the cost we can make it. The bottom line is that most of us home-brew because we love beer, we are creative, we like doing things ourselves, and we enjoy sharing our creations with friends and family. Like any other activities that we take up, it is often worth a couple bucks if it makes it that much more enjoyable. I could not even add up all the money I have spent over the years on fishing, shooting, skiing, golf, etc. I still enjoy all of those activities, and I now put brewing at the top of the list.
My advice to anyone considering home-brew:
Start with a kit brew and work your way up as you learn.
Read & learn all you can about the process, and beer styles
Make a point of trying and appreciating different beer styles
(If all you enjoy is the Big 3 light beers, Home-Brewing is probably not for you)
Enjoy the process as much as you enjoy the results
As you learn more and find how enjoyable it is you can move to All Grain and other processes
Cheers!