Does anyone know of a good protein for homemade RTDs. It's hard for me to mix shakes at work, so I like the RTDs. However, drinking a couple of those every day can get expensive. I've tried premixing shakes in the past, but by the time I drank them they didn't hold together very well.

As far as protein goes, I want a whey protein isolate with 40-50g.

Any ideas?