I know there are other ways to get discounted Soylent Drink, but I found someone selling cases for $28/each and bought several cases from him. He delivered, so I thought I would pass the link along. It looks like he has an unlimited supply. (not sure how he gets it so cheap)
Edit: Listing ended, but you can go directly to his listings in his profile and he has another listing that is live: http://www.ebay.com/usr/mightysaintjohns?_trksid=p2047675.l2559
I know you get 2% back in eBay Bucks for spending on eBay and also can often find discounted giftcards or coupons online various places for eBay too.
Just another option for those looking that I thought I would pass along in case it helped anyone out.