Myprotein shipping is a flat 4.99 I think so the more you buy the cheaper per kilo, but 24.99 for 5 Kg is very good.

One thing I do like about Myprotein is the chance to mix your own blend, not sure if bulkpowders allow that. I tend to go for a blend with 5% L-Glutamine and 60% Veggie Whey 35% Casein.  You can opt to add fine ground oats, flaxseed oil, allsorts.