Put probably not cheaper than grocery shopping for a month for one person, unless that person has particular food tastes that Soylent isn't going to address.
Multivitamin ~10$
1 gross eggs ~20
30 cans refried beans ~20
~100 small tortillas ~7
5 lbs rice ~5
3 lbs sour cream ~9
salt ~.7
pepper ~1
garlic ~2
10 lbs potatoes ~10
spend the remaining ~3/day on whatever you feel like. suggestions include: pasta and sauce at ~1 a meal.
whole fat chocolate milk at about ~2 a day.
a pint of olive oil a day.
a case of ramen a day.
a pint of ben and jerry's (there's 2000 kcal by itself).Prices sourced from an H.E.B. supermarket in Austin Tx. Oh, also, I've been living on less than 3$ of food a day for the last year, so this isn't exactly theoretical. 230 per person per month would the height of luxury for me.
I highly recommend you switch to brown rice, wheat pasta, beans, produce, and cheap cuts of meat. Add in a slow cooker if you don't have much time.
Oh, and as for this soylent product, I would run screaming away. I only read his recipe up to the carbs section, and the fact that he thinks all carbs are the same because they end up as ATP is mind-boggling. It's as if he isn't aware of the huge problem with HFCS. Any biochem undergrad can tell you about the incredible complexity of the feedback and regulatory mechanisms of the body; to focus only on the end product of a mechanism is ignorant at best.