Yes you can. the first thing that you need is a herbalist. they make the mix to get the desired results. then you have them made and bottled. And then sell and ship.
You can remake any supplement, relabel it and sell it. Since most pills are classified as supplements in order to avoid FDA scrutinization this makes them in essence a "food". Since they are a "food" their formula is not patentable thus you can replicate it. As far as costs, depending on ingredients and assuming you want a decent label and not too much inventory (say a 1000 bottle initial order) you are probably looking at $5-$6 per bottle. If things get rolling and you are ordering 10,000+ bottles at a time I'd bet you can get it for under $4/bottle in your warehouse.
There are also places that specialize in storing/processing orders for other ppls products. You would order/pay for the product then they warehouse it and ship it from the orders so. At that point all you do is order more product as needed and maintain a website to keep orders coming in. Probably a good idea to invest in liability insurance too in case someone gets sick.
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