I've been in good shape, protein powder-wise, for the last six months.
That's mainly due to shopping at two stores: Vitamin Shoppe and GNC.
At Vitamin Shoppe, I hit their clearance table in January and got thee 6-lb jugs of HDT 5+1 Whey Protein for $10 each. This, along with a bag of EAS Whey protein I got at Sam's Club ($28) kept me in business for 2-3 months.
The other clean-up came when it had the "Buy One; Get One 50% off" all Vitamin-Shoppe-brand products, including the BodyTech line. So, I ended up with several 5-lb jugs of Whey Tech protein powder, which retail at $30 ($28 on vitaminshoppe.com) I also managed to get (from the clearance table) a 42-serving box of MyoPlex for $45.
As for GNC, it's all about the markdowns, particularly with the RTDs (CytoSport, IsoPure, ABB Mass Recovery, ABB Extreme XXL, etc). all of which were marked down to as little as $0.99.
Vitamin Shoppe also had some IsoPure RTDs, marked down to $1.89. And, those were the Passion Fruit ones. I never knew that it came in that flavor. It's quite delicious.