Pricing really depends on your power requirements. There are automatic standby systems that go for under $2,000, but they're only in the ~6kw range. Depending on your house, that might be enough to run everything. For me, with a 200amp service, it's not even close. If you own a mansion with a 400amp service, you're looking at spending a lot more.

The 20kw units we ordered are about $4,000 a piece shipped with the included transfer switch. We'll run the gas lines ourselves and my friend, an electrician, will install the transfer switches. We're figuring total cost should come in well under $5000 a piece, but if you had to hire someone to do the installations I'm sure you could easily eclipse that.

All in all, the first thing you need to look at is your power requirements. Then, look at applicable generator setups. At that point you can start to see how much money you're looking at and get estimates on installation.