Any thoughts on on buying vs. leasing the propane tank, and methods of getting better deals on propane for home heating?

I currently lease my tank, and when I bought the house, I signed a contract that stated the price of the tank if I wanted to buy it. It originally started off about $1400, but I negotiated with the guy to around $925 buyout. This is for a 500 gal, in-ground tank.

If I purchase the tank, then I can shop around for propane suppliers and get 20 to 45 cents off per gal. I am currently paying a rate of around 2.10 to 2.15 right now, and I have always been unhappy with my supplier, as my sales guy is a jerk. I have requested to the district manager that my account be given to a new sales rep, but no word yet on that.

So, pros and cons of lease vs. buy, or any other methods found to lower my heating costs (other than the obvious insulation tips...my R-40 in the attic sits pretty tall..