Inflation calculator. I use this site all the time. Whenever a novel mentions a dollar amount for something we convert to today's value (e.g., Daisy Buchanan's pearl necklace was $300,000 in 1925 is worth $3,886,207 in 2012).
This sight converts dollar amounts from the past into today's value. Great for teaching church history! For example, in 1829 it cost $3000.00 to print the BOM. Today that would be over $76,000.00! The kids relate to Martin Harris' material sacrifice when you teach it with this amount.