I notice the difference between the straightforward meal replacement and the athletic protein powders is the latter add additional amino acids and muscle recovery components into the mixture. Glutamine for example. Some add Creatine for pre-workout benefits.etc.
If you have a Costco nearby and are a member, the most recent coupon flyer has Optimum Nutrition Whey Isolate Vanilla, 4.5lb bucket for $12 off retail so it is $45.xx before taxes. A very good deal. Low cholestrol, reasonable carb, mucho protein. (I bought it for me wifey and she is a zumba/yoga/step aficionado etc.) Isolate is the low cholesterol version.
Iso Sensation 93 unflavored is currently $50.xx at Lucky Vitamin. A bargain as I bought pre-special and paid $63.89 at Amazon.(Oh well, I did get triple points)
I have to pitch some friends. Sunwarrior.com does Rice protein. Very high production standards but expensive.
There are others. Very knowledgable fellow over on the C-D Exercise forum recommends Dymatize 100,etc.
I would avoid the non-Isolate Whey Proteins as they have much cholesterol. Cheaper brands have much filler.