I own my 500 gallon tank. Most used tanks in my area will cost about $1/gallon or less. A 500 gallon tank in good condition will be $400-500. A 1000 gallon tank $900-1000. You can rent them from suppliers, but then you have to buy their propane and pay monthly rental fee. Usually, after several years of renting, you could have owned your own used tank for the price of renting. Propane guy told me that above ground tanks last a very, very long time. Tanks in the ground can rust out and won't last as long. The valves or guages can be replaced if needed. We have tanks on the farm over 50 years old and in great shape. Just need to paint them once in awhile to stop the cosmetic surface rust. Even if you rent one, it may be a used repainted tank.
If you plan to use it for a long time, then consider buying. If you plan to move or quit using in several years, then rent.
Propane suppliers prefer 1000 gal tanks for residential use because they don't have to fill them as often. I have a large house and it is probably better suited for a 1000 gal tank. There is no charge for delivery and I am on a "keep full" policy. It is their responsibility to make sure I don't run out. If I do run out, then they have to purge all the lines and restart the fireplaces, stoves, furnace in my shed and water heaters at no cost. I have run out about 3 times over the past 7 years. It takes them about 2 hours to get everything working. (You would think they would learn.) They will even come out at night or on the weekend in the winter if I run out. (Been there, done that.)