I'd imagine it's similar to or cheaper than most people's food expenditures. If they actually can make it significantly cheaper, it could be a big deal.
I suppose sending it all to one place in big chunks makes it seem scarier, price-wise, which could be a problem for them. Food expenditures usually dribble out. They may want emulate that in their sales model, at least initially (weekly recurring transactions, or something.)
You're down to $3 a meal. Unless you're eating fast food or nothing but pasta... good luck finding another way to get to $3/meal.
[edit- Important clarification: I'm talking about a nutritionally complete, paleo-ish diet of healthy foods (which is what this is targeting to replace).
Of course you can eat for less than $3/meal, but you start to include less healthy things like chips, breads, pastas, etc. This is not the meal Soylent is intended to replace.]
Everything under $2/meal.
Afternoon meal: sandwich, maybe bag of chips ($1.00-2.00 per person).
Evening meal: meat, vegetables, carb ($2.00-3.00 per person).
I guess if you compare it to eating out it's pretty cheap, but if you compare it to cooking (although there isn't much cooking in the mealplan above, really just dinner), it looks pretty pricey.
Browned the meat, put the rice in a skillet, cut up meat and put it on top, put potato slices on top of that, covered and baked for 45 minutes. Total prep time, 5 minutes, cost about 6 bucks. Feeds family of four, and had leftovers.
Some other recipes include things like a ham and noodles w/ cheese casserole (egg noodles, and a ham steak cut up on top), for around $6 to $7 or so; beef stew -- $4 to $6 for the stew meat, plus $1 - $2 for a bag of frozen mixed veggies and a couple potatoes; and variations on chicken fried rice, and even fajitas are all less than $10 a meal. Actually, the fajitas can go up to $15 if you get beef instead of chicken. And these all feed a family.
Do you pay for shipping for Soylent? Because that's already going to cost more than cooking multiple meals.
($65 per week is £40 per week. That's doable.)