paying for bariatric protein shakes and vitamins

You can buy primer protein with your food stamps! Anything that say nutritional facts you can buy!

They sell the Ready-to-Drink Premier Protein at Walmart which is a great choice. If you can buy buy protein powders on Food Stamps I bought a really good one at Walgreesn when I was out by my son in Chicago from Bodylogix it was a big brown container that said Natural Whey on it. Remember you will be spending much less on food.... My surgeon recommends a protein drink a day for as long as you are losing weight. You have to see your surgeon's recommendations. Just so you know what to look for:

Premier Protein

Bodylogix Natural Whey

I can't offer you no cost, but I can tell you my low cost choices, because we are a family of 6 without assistance, so we have to be very careful how much we spend.  Body Fortress is the protein powder I use and I really like it.  It's $14.99 at WalMart, but if you buy it from WalMart.com, it's $35 for three with free shipping, so $11.67 each, which is really good!  Three tubs will last you a while, and you can choose 3 different flavors if you choose.  I like the chocolate, vanilla & strawberry, but not the chocolate peanutbutter -- but that is, of course, personal choice.
For multivitamins, my surgeon just has me taking Centrum chewables, also quite reasonable at WalMart, and there are often coupons for Centrum.