Underground is the way to go. If you are going to spend the money to bury an underground tank, you might as well save a small fortune and go the 1000 gallon route. The cost for a 1000 gallon underground tank is not twice as expensive as a 500 gallon - it was only 50% more expensive back when we had them installed. The cost to bury a 1000 gallon tank is the same cost as burying the 500 gallon tank. Excavating the larger hole only takes a few more minutes to do. Also, the 1000 gallon tank makes it immediately possible to save 40-50 cents per gallon when you are purchasing more than 500 gallons. Different suppliers have different rules. Speaking of different rules I recommend staying away from any business that falls under Suburban Propane. They have a really ridiculous "contract" that they require, and if you agree to all of their "rules" they have all sorts of rights to trespass on your property unannounced - to perform "safety inspections" - not something I'm willing to tolerate.I was quoted $4000 for purchasing a 500g underground tank, installed 2 or 3 years ago. Have prices come down ?