That's where I disagree. If you dont' have the money to buy pure whey isolate only, don't buy any whey. With supplements you get exactly what you pay for. $30 for 6lbs will most likely get you a crappy mixture of mainly whey concentrate and fillers, which not only won't help you much, but it will most likely give you candida (99% of bodybuilders have it) which will give you a whole host of other problems. Plus all the gas, bloating, etc that won't make you a happy person. BTW, that's how you know that your protein powder is quality - you get zero bloating and gas from it. The bloating and gas comes from fillers only.
If you can't afford the proper whey, stick to food. It will do you much better.