https://www.google.com/#hl=en&sugexp...w=1598&bih=819
You can get them all over the place. I'm not sure what site my company picked them up at but they came to $20 after shipping. The GreatStuff gun really isn't the end of the world. If you don't use it day in and day out it will probably last a long time. The thing is that the HT300 is a much better gun and is cheaper, so why not? Unless, like you, you already have one. The last on in my company was decommissioned last Tuesday. The second to last one died a little over a month ago when I was using it. I had just put a new can on and the gun wouldn't close. It emptied an entire can on a bath fan. That was a nightmare.