TLDNR: probably not, unless you like buying 9 months worth at a time.
So I ordered some stuff from bulksupplements.com through amazon (choline and potassium citrate) and was looking at some of the other stuff they sell. Among others, they have pure calcium citrate, magnesium citrate and vitamin D3. The one ingredient I go through faster than any other is the NOW foods Calcium & Magnesium – 8 oz. – the price on it tends to fluctuate a lot. I bought it last week for $12.27 including shipping, now it’s $10.17 including shipping and I think at one point I got it for $6, I started wondering if I could mix my own equivalent for less.
So I ran the numbers. The first thing to be aware of is this handy note from bulksupplements about the D3: “This supplement contains around one hundred thousand IU per gram and has no fillers of any kind present in it.” So 1g has 100,000 IU in it? holy crap! Check out the rest of the warnings on this page. Based on that, I’m thinking it’s prolly not worth doing the D3. Not when I can get caplets of whatever dose I want from Wal-mart for $0.06 a dose.
Let’s ignore the D3 then and talk about the calcium and magnesium. Based off the labels, I’d need 2.66g of Magnesium citrate and 1.92g of Calcium Citrate to get the 400&400mg of actual Magnesium and Calcium that’s in the NOW which has 50 doses per bottle. If I buy 500g bags of both and make 500 doses it’s going to cost me $9.69 in bulk ingredients. If it get all nuts and buy the 1KG bags, each group of 50 doses will cost me $7.43 (both figures assume free shipping). It would result in using 3.54g of Magnesium Citrate and 2.54g of Calcium Citrate daily to equal the 6g of NOW that’s in People Chow 3.0.1.
End result: yes buying the bulk powders and mixing your own *would* save you money. But you’ll need to buy it in 1kg bags (which would last 282 days for the magnesium and 393 days for the calcium) in order for it to be cost effective. You also would need to either get a scale that can measure 2.438mg of D3 for a day or use a capsule supplement.
More fun facts: getting the 1kg each of the bulk powders would cost you $63.92. To get 282 days worth of NOW Cal/Mag/D3 would be 8 bottles, and at today’s rate of $10.17 that’s $81.36