Two companies in this guide publish installed prices on their own websites — Long Island Electric Co. and Marra Electric. Every other installer prices your job after a site visit. So the figures below are those two companies' own published prices, used as local context — not a quote from any other company in this guide.

Taken together, those published prices put a typical installed standby system in Nassau and Suffolk roughly in the $8,000–$18,000 range. Treat that as context, not a quote: your home's size, fuel supply and electrical setup move the number.
No published price for a portable generator or for an annual maintenance plan was found on the own websites of the companies in this guide. Ask each installer what maintenance costs and what it includes, and get the installed price in writing with the scope itemized — kW, brand, transfer switch, permits, gas line and warranty.