I've heard of people refilling those portable camping propane tanks at home. But you need to know what you're doing.
It's a risk I personally wouldn't take though. You might save money by refilling those portable propane tanks but it could end in serious injury or even death.
You can look at youtube and I'm sure that's where I saw video of someone refilling those camping propane tanks but do so at your own risk.
If it were me though I'd just get new ones to be safe.