Protein Quality; 2lb vs. 5lb?

Having just read this issue’s (#125) BTS, Tim said that it was impossible for a quality 5 lb whey to retail for less than $70-$80. I myself found it odd that some proteins retail for $40 for 2 lbs. then only $45 for 5 lbs (same brand). Several weeks ago, there was a thread on the 5 lb containers and we discussed that the 5 lb were more inexpensive per gram since they did not contain some ‘bells and whistles’ such as extra glutamine, vits and mins, etc. and thus the lower price per gram. I also attributed relative ‘volume’ buying as a factor in the lower price. Though I find it hard to believe that ALL the 5 lb wheys are of relatively poor quality since every mega power in the industry sells one for approx. the same price, I am not so sure now. As I use a ton of these proteins in addition to my MRPs daily as I’m sure many of you do, I’m now concerned. Any thoughts out there?