Then, just consider all of these costs rising at a rate of 25% yearly for the next 10 years. When I talk about $5 heads of lettuce, I am not joking.
Not anywhere near that severe. Labor is only about 20% of the overall cost-of-production. Illegal aliens make-up roughly one-quarter of the workforce in Agriculture. If the hourly cost of labor quintupled to $25/hr as a result of labor-law enforcement, the total cost of production would only rise 10%. Given a 15% net-net, the price of lettuce would rise roughly 15% over current prices to make up for increased labor cost.
Given that a head of lettuce currently goes for about $1.25, the resulting head of lettuce produced by legal means would go for $1.50-ish.