One way to make an expensive ingredient into a less-expensive meal is to make it the only pricy ingredient on your list. This means, basically, prioritizing. You'll often be prioritizing your protein, which is typically the most expensive element of a meal.
Dying to have lobster for dinner? Combine it with cheap (but tasty) ingredients in the form of a lobster-mushroom casserole or lobster mac and cheese. This has the dual effect of making the lobster your only real expenditure and decreasing the amount of lobster you need to include per serving.
You can satisfy a lamb craving with a stew, a need for crab with a quiche, and a desperate desire for filet mignon with reduced portions complemented by a pile of potatoes and green beans you buy in bulk. You'll be eating potatoes and green beans for the rest of the month, but it's worth it.
Which brings us to the next tip -- one that will help make a month of green beans and potatoes more appealing ...