[I have this unit also. We installed a 500 gallon buried tank, which I believe ran about $1000. I also use the LP for fireplaces and an on demand hot water heater. No power outages yet.
Brian
Good to know, I didn't think about the buried route after I had all sorts of problems looking at doing a buried 1000 gallon oil tank. Insurance companies apparently do not like that and (probably rightfully so) wanted all sorts of leak detection systems which made it more of a project than I wanted to take on.
For gas though, I guess it would be different. 500 gallons sounds like a reasonable amount, what kind of run time would that give you? The price seems a bit more reasonable (versus over $10k just to start talking about putting gas in).
I moved on from that project but good to know as I would not mind having a standby generator at some point in the future.