Smallish butane gas torchs are available everywhere, a quick search found them at Jaycar and Aztronics, I bought mine from Bunnings, all for around the $30-$40 mark, they can be filled from gas cans which are around the $15 $20 mark, the brand of mine escapes me but it has a self lighter and is quite economical on gas. The gas cans come with a variety of tips to refill all manner of devices.
You don't use the flame on heat shrink, just the hot air at the end of the flame cone! Don't be tempted to buy those small $10 gas torches from the store counters and cheap shops, they are a waste of money and pure junk.
My daughter has a very small compact hair dryer which may or may not work, I haven't tried it, I imagine it would, a quick test certainly made me go 'ouch'.
I have on many occasions used the soldering iron that I just made the connection with, just run it all round the heat shrink to make sure it all gets shrunk. I recently put heat shrink around a TCS Z2 chip and used the soldering iron on that, I wasn't game to go near it with the butane torch. It worked for me.