I'm getting shafted on tank rental and high prices, but I'm a low volume user.
I just have a "decorative" propane fireplace - inefficient, but does provide some heat. I pay $100 a year to rent the tank (100 gallon tank), and I don't know what the per-gallon charge is because I haven't filled it in two years and it's still showing 60% full.
Best thing I ever did was to figure out that the pilot light was using 2 gallons a week. The first two years I was in the house, I used 100 gallons a season. Now, it's looking like I might make it through a third winter on the same tank. I have to start the pilot light every time I use it instead of just hitting the button on the remote, but that's no big deal.
I think I need to empty this tank, tell them to come and get it, buy a 40 gallon tank, and shop the fill prices.