For calcium/magnesium/potassium I buy GNC Calcimate Plus 800. I got 240 tablets for $20, and if you have a gold card, you can get the second bottle for 1/2 price.

For protein shakes, I have been using a brand called Nature's Best Isopure. I use it because it has 50 g of protein per serving, it also has 5 g of glutamine and some other things too. The chocolate has 1 carb and tastes good, strawberry has zero and tastes ok (I still count it as one carb, it has sucralose). They also make vanilla, but I haven't tried it yet. It is expensive, $45, but they do last a month or so.