Generally speaking a residential windmill will not be a very good financial proposition. It will take significant tax credits, depreciation, and other incentives to even approach financial breakeven. In addition, a wind mill must be located in an area with proven prevailing and steady winds. Not always easy. For example, if it was your intent to provide for your personal needs of , say, 7500 KWh/year, the conventional wisdom advises that you would have to build three (3) plants of that size in different locations to account for the variability of the wind. Wind is not a particularly good base load generator.
This discussion doesn't even address space issues or noise, or maintenance. There are better options.