I did a cost vs make my own analysis on this before and it was very close. I probably spent around $40 a week or about $7.50 a day on lunch when I bought. I think i broke even because I made very hearty, large sandwiches every day even when I made them. You figure $2 for bread, $10 for meat, $5 for cheese, another $6 for tomatoes, lettuce. Another $5 a week on Chips and another $5 a week on drinks. That comes out to $33; I only gained $7 a week when making my own; yet the amount of work that went into it was a pain in the ass.
Perhaps look into Subway; they have a $3.99 daily combo special now.
2jZ + RB26 + 4G63 + LS9 + N54 =