Just had my neighbor who's a propane dealer pick me up a used 1000 gallon tank.   Looks like around $1,200 with all new valves.   I'm adding it to our 500 gallon tank solely for extra capacity to run the backup generator.   I was once out of power for 12 days and had a major snow storm in the middle of that outage.    I'm not taking any chances on not having enough propane.