I use Twinlab 100% Whey Protein (50g per 2serv). Is it good enough because I can not afford GNC?

GNC sucks. Overpriced and generally a very unknowledgeable staff. I’m not a big fan of Twinlab products either. Their quality isn’t all that great.

I get my supplements from bodybuilding.com. The prices are very competitive for high-quality products. I’d recommend looking into protein supplements by EAS or Optimum. I primarily use EAS Myoplex.

Check out http://www.bodybuilding.com/store/goalprotein.htm

There are a lot of choices there.