29 bucks is actually pretty cheap for 5 pounds of ON whey, that's what it goes for on bb.com, you'd pay at least 40 bucks at GNC.
Not necessarily. With the Gold Card, that price drops to $32. That's assuming you don't get any markdown jugs of the stuff. The cheapest I've ever purchased ON 100% Whey (Gold Standard) was $20 (a jug, marked down to $25 plus the Gold Card discount).
If 100% Whey (Gold Standard) is too pricey, you can always opt for ON Classic Whey. It doesn't have quite as much protein per serving (21 grams vs. Gold Standard's 24 grams) and there's no Aminogen in it. But, it's quite economical as well, especially if GNC marks it down.