Saving money is all relative. Being that drinking beer is not necessarily a necessity, all of it could technically be saved, whether you buy it from the store or make it yourself.
This arguement happened often with my other hobby, motorcycling. The initial cost of equipment, and getting started make it seem like you can't save money and some guys would argue you wouldnt. Well let me tell you, I've done the math and my bike has more than paid itself off including equipment, tires, insurance, etc when you figure the gas it would have cost to drive my truck over the past 3 years.
You can look at brewing much the same. It may cost a bit up front (equipment, extract, yeast) but once you go AG, slant yeast, grow hops, etc it will definitely pay itself off over time. If you think about it some of the six packs we buy at the store cost over 10 bucks. Even at the worst case scenario youve given $70 that should make about 50-60 beers. That would cost you about 100 bucks at the store if you bought it retail. So you are already breaking even at worst. However, one could also argue the time you put into it you could out weigh the dollars you save. After all, what price would you put on your lifetime? The argument could go on and on.
Personally, I try not to think about the savings/cost and just enjoy it for what it is. Fun times and great brews I can call my own.