I bought my own tank this summer and installed it myself. It took A LOT of calling around to find someone that would actually sell me a tank other than the company that already had a leased tank on my property. The local company had a 330 gallon tank on the property from 1984 that has been here since 1985 and never serviced. Original regulators, the secondary would only put out about 10.5" WC so it was worn out. They wanted $1400 to leave that leased tank here and call it mine.
I got a 500 gallon refurbished tank for $350 I think and they gave me half off on the first fill. Prices were down during the summer. IIRC, I was around $800 for the tank and propane, plus the $150 I spent on the 100' of buried coated copper line and both regulators. I paid a buddy with a ditch witch $50 to dig a trench. All for about $1000, I got my own 500 gallon tank installed and the propane to go with it. I can buy from anyone I want to, but I'll probably stick with Southern States since they seem to have the best prices around here.
I run the furnace in the fall and spring when I don't need heat every day. It's a lot easier than building a fire every few days. My stove is also propane. I'll wait until I need at least 250 gallons to top off since the propane guy said it's cheaper to buy in bulk like that. I was going to only buy a 250 gallon tank, but the propane guy at Southern States talked me into a 500 gallon tank due to the buy in bulk argument and the fact that the bigger tank was only $50 more.
I'll also buy during the summer. It should be a few years before I need to top off.