How much you save depends on the depending things.
I can get my 2-row from RiteBrew.com for $38 for a 50# sack. They're about 3 hours up the road from me, and I'm by there once or twice a year. I also have a friend who heads up there occasionally who'll stop and get stuff for me. Thus, no shipping, and I'm looking at 76 cents per pound. Maris Otter, which I use a lot of, is about 99 cents in a 55# sack.
My (relatively) LHBS has base grain for $1.50/lb. I think that's crushed, but either way, look at the difference. I can do better in some places, but I have to diddle around a lot to get things to come out cheaper. So I buy bulk from Ritebrew. I haven't asked my LHBS about bulk grain, if he came close to Ritebrew I'd get it there.
I put in an RO filter; saves me about $5 in water each time bought from the store. I paid $175 for everything (dissolved solids meter, a few extra doodads, shipping), and I've saved about $75 in water so far.
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Many above talk about being able to control things; very true, and there's an additional advantage. I store my grain, for the most part, in sealed containers. It keeps. Crushed grain will go stale.
But in the end, if this hobby were purely about saving money, we probably wouldn't do it. I've got, <mentally adding> well over $1000 in kegs, keezer, lines, faucets, regulators, tanks......$175 in a RO system...$100+ in a ph meter...$160 in a kettle...a grain mill for $130...another $200 in brewing ancillaries....a ferm chamber fridge for $100....couple of Inkbirds for $80....fastrack $40....laststraw beer gun $100....I'm going to stop here because I'm scaring myself.
If I don't include my time, I figure I'll break even about the year 2027...assuming I don't buy anything else. And the odds of that? Zero.
We do this because we brew better and interesting beer, and because we like doing it. Very few who do it well are going to save money, at least not for a while.
PS: I've got a Blichman Hellfire propane burner on the list....$200. Maybe I can get someone to buy it for me as a Christmas present.