Do not forget to add the cost of electircal work and permits etc. Also fuel issues Natural gas lines break as they did in certain areas with Sandy and Gas can not sit forever.

A cheaper method may be a small or medium size honda generator. No cut over switch just common sense about what you decide to plug in via extension cords and the amp/current draw.

A big caution with all these generators is make proper exhaust far away from people or living areas. Many people died in Arizona swimming near house boats before they connected carbon dioxide as a cause of death.