I just finished my last 20kg bag recently and was shocked to find that prices have doubled since I last purchased! As far as I can see, the price for the same bag is $600+.
Rogers & Co Foods is actually where I bought my first big bag of WPC many years ago. Good value then and even better value now, it seems. I just picked one up and it's NZMP/Fonterra brand (made in Aus). Note that this is totally unflavoured (but does have lecithin in it for easier mixing), so you need to add the flavouring of your choice, or just drink it as-is if you don't mind the taste.
You must be hoooge after finishing a 20kg bag. What is the typical expiry of these?