Why would the cost come down? Well, I'm calculating every single cent I have every spent on equipment, ingredients, my KLOB membership (costs $15/year but gets me 10% off ingredients), the Scotch that I put in one of my beers--everything, not just ingredients. Basically what's happening is that the initial and occasional investment on equipment has gradually proven its value and now I'm mostly paying for just the ingredients to make the beer. How much are those? A 5 gallon of, say, Two Hearted will cost around 30 dollars to make, getting you around 45-50 beers. That's about 4 dollars per six pack. Most recipes will be cheaper than that. I made a nice brown ale for $17 and got 43 beers, which is only $2.40/six pack. So my cost should go down a little more but probably not below $4. All grain brewing, which I purposely don't do (I do "partial mash"), could potentially save more money, but comes with a huge initial investment on equipment--so the savings wouldn't show up for a while, at least a year I would say.
There's a shit load of things that I did to save money. I only bought what I needed. I reused yeast (that's a big one). I used sugar. I took good notes. I borrowed stuff from friends. People gave me stuff.
Yeah, but don't you drink more? Ummm....I don't think so, although this is a very good worry to have and I've noticed that home brewers never talk about it. My wife says I don't, so I trust her more than I trust myself to answer that. I agree with her. I blame it on becoming an adult. I certainly drink more frequently, but only one or two beers at a time, probably averaging about 22 oz. of beer per day. I believe that's called moderation. Of course sometimes I do have to test out the alcohol content of my beer (too cheap to buy a hydrometer which measures that), and so I will go ahead and get drunk just as a test. Just as a test , not because I want to get drunk off the delicious beer I've made. Course not.