When people ask that question, I love to tell them the best post I've ever seen on this forum:
"Getting into homebrewing for cheap beer is like buying a boat for cheap fish."
What it gets down to is that you spend money on the ingredients - and how much you spend depends on where you live, what the market is like, and how much you buy at a time.
But, as has been mentioned before, the cost of the INGREDIENTS is only a part of the cost of the beer. Equipment costs are up there too. And don't forget the cost of the propane to boil the water (or gas, or electricity, or whatever you use), and the costs of the cleaning agents and sanitizers.
Once you're in this hobby, you'll constantly find yourself buying this gadget or that, to improve your process . .. or upgrading your equipment . .. or buying new equipment to replace the stuff that's worn out.
Truth is, I've brewed 40 or so batches, but I've probably spent $800 on equipment, gadgets, and "stuff" . . . so if I was being honest about cost, I need to add about $20/batch. Figure I get 8 x 6 packs in a batch, that means that the EQUIPMENT COST of each batch is around $2.50. Then add it ingredients at about $40 a batch (plus or minus, depending on what you brew), so $5.00 per 6 pack, and even after 40 batches, I've still payed about $7.50 / 6 pack . .. and I got my friends to GIVE me bottles (and have saved and reused them plenty).
Oh, and next week I want to upgrade my propane burner (about $150) and my brew kettle (about $100) . . . so it's not looking to get any cheaper
That being said ... I don't do this to save money on beer. I do this because I ENJOY MAKING BEER. It's fun. It engages my inner scientist and inner alcoholic

And it's STILL cheaper than that fishing boat I was looking at . . .
