OpenEI.org has this wonderful resource for showing the costs of various energy technologies. The Transparent Cost Database covers Wind, Solar, Coal, Natural Gas, Geothermal, Hydro, Fuel Cell, Nuclear and shows cost projections out to the year 2050.

All of the long established technologies, coal, natural gas, nuclear, and geothermal have had their designs optimized as such the predictions of future costs are relatively accurate. For the newer technologies PV solar, thermal solar, fuel cell, wind, the numbers are already on the high side due to newer technologies and continuing research.