2 Answers

As to your question of how much it costs to install such a unit.  It depends upon how large of a unit  is needed, and if it will run on propane, gasoline, or solar.  It also depends upon your local economy, within the US, there are huge differences on costs of living, internationally, it would also be true. 

If you have electric clothes drier and a basic understand of electric circuits it is relatively easy, since you do not need to pay an electrician.

All you do it attach a 250V plug to the outlet of your generator and plug it into the drier outlet, after you have pulled the disconnect on your Service Box.

Then you can run any combination of electrical appliances, up to the capacity of you generator