A clever fellow at my work posted a link to Numbers everyone should know. When speed matters, you need to know what is cheap and what is dear.
Dear Oscar Wilde said "What is a cynic? A man who knows the price of everything and the value of nothing." But Alan Perlis countered, "LISP programmers know the value of everything and the cost of nothing."
Learn your costs, the value you get for them, and the price you pay.