I guess location, location and location are the most important things. They go with the market.

In 2010 I had a 8KW Generac automatic standby generator installed, soup to nuts, for right around 5K. Permits, all included. No concrete stand, but a composite material base that seems to be working fine.

Note, that I did not have to have a larger natural gas pipe (from the street to the house) installed (this can be a problem in older areas), but did have to have the "limiter" removed (dig up the limiter near the street and remove it, fix the hole etc.) and a larger capacity gas meter installed. This was included in the price.

I had a previous estimate of 10k: way beyond our means, so some shopping may be worthwile. 5K is a big variation for the same thing. And the company that did it is a big local contractor, and I got a 5 year guarantee.

However, in our area, over last year or 3, there are a lot of "guys with pickup trucks" selling these things, installed. IMO, go with a company that you can expect to be around for a while.

We have been very pleased with our system -- it covers all the critical things in our house, but not everything. We can live with the areas (e.g. bedrooms) that don't get the emergency power.

The peace of mind when you are not home and the power goes out is, well, not priceless, but sure worth what we paid.

Good Luck!