You can get a 5lb container of whey for about 40 bucks. It'll last you for months if you do a scoop a day like I do.
I would say dont believe the hype with the performance drinks overall. Whey is a nice little supplement post workout, but make sure you're getting the vast majority of your nutrition from whole foods.
I like to put a scoop of whey in my morning oatmeal and then after a workout I sometimes have a simple shake of milk + a scoop of whey.
I personally order from here and never had a problem with them:
http://www.dpsnutrition.net/Specifically I get Optimum Nutrition Strawberry 5lb:
http://www.dpsnutrition.net/get_item_on016.htmLove the flavor although I hear the chocolate is really good too.