Just be very mindful of the carbs. A lot of protein powders are also high carb, so you have to check. And there can also be quite a bit of variance between flavors even in the lower carbs ones, so watch for that as well.

I use Optimum Nutrition - usually the Vanilla Ice Cream (3g/scoop) or Any Whey (unflavored, 1g/scoop). Most of the flavored ones I have seen from them are 3g or less. Vitamin Shoppe usually has the best prices on it if you have one local to you.