From what I understand, there are only a few protein manufacturers in the world, and different companies buy it in bulk, add in flavours, etc, and re-sell it. I have no idea if it's true or not (just what I heard), but the reason there are cheap types of proten is because of what they cut it with. It also accounts for the "tin can" taste of some of the shakes.
I use the PVL line; not only is it supposedly higher quality, but the flavours are miles ahead of the generic chocolate and vanilla on the market. My fav is the peanut butter.....suuuuuper tasty. You can get it at any GNC in the city.
www.pvldirect.com is their web address.