@PRRick posted:Check ebay, there are a few listed for $30 with free shipping.
Be careful, if you're doing custom installs, you'll likely want to create a stack extension. Most of those have fixed funnels, and soldering a brass tube to them usually loosens them from the PCB. I buy the ones with the threaded stack, and the separate brass funnel. I can solder my stack to the funnel and then screw it into the smoke unit.