I recently bought a second-hand scroll saw (Clarke) for my first foray into this part of woodworking. Old but barely used. Of course the bladder for the blower was shot. I can get replacements from the UK but at nearly 4 pounds they're expensive for what they are and getting them to South Africa makes it out of the question. I saw that people use aquarium pumps but came up with another solution I haven't seen elsewhere. Maybe it's been tried of done before, I don't know. I attached a bolt to the saw arm going through the hole in the metal cover to which is bolted a tap washer going into a short piece of PVC pipe with a plastic bottle top and pipe attached. What can I saw? It moves plenty of air. I can't say about longevity yet, but it's cheap and uses stuff I had lying around.
Here's a short (un)professional video (hope this works). If you want to know more just ask, I'm happy with it and it will do the job. And, no, it doesn't suck
VID_20181220_190359.mp4