You may want to check out PlantFusion as an alternative to Vega. it contains pea, artichoke, sprouted quinoa, and sprouted amaranth. Although quinoa and amaranth are often called grains, they are seeds. Overall it should provide a complete protein profile, I think. It mixes well and I like the vanilla flavor.
I've also seen beef and collagen protein sold. Here's a link to a "Paleo protien powder" http://paleoproproducts.com/
Made me bloated and constipated... uhhhh I did make some pretty good Pumpkin dessert with it (pumpkin mix with powder, pumpkin pie filling)
the brown rice part makes sense and is only a portion of it and i can say it's one of the better tasting shakes on the market for sure, and it doesn't upset my stomach which all whey shakes did.
i personally would use any protein powder other than unflavored whey, it really is the best...pumpkin seed and hemp seed arent that bad though. if you can get past the taste spirulina or something similar would be better.
that vega protein uses pea and brown rice protein. ive heard some decent things about pea protein but ill warn you that brown rice protein tastes terrible, and obviously wouldnt really be paleo.
also i know beef protein powders do exist...i dont know if there are any out there that could be called natural, but if there were thatd probably be about as paleo as you could get.