Total meal replacement shakes exist, although I have no idea about pricing. However, going down this route is basically ensuring sub-optimal nutrition.
Very nearly every other diet is also sub-optimal. Most of them are quite probably worse than what we can do via supplementation.
Rob Rhinehart's food replacement Soylent now has a crowdfunding campaign.
If you're interested in one or more of these benefits, send in some money! There is also a new blog post.