On Mar 17, 4:32*pm, mike wrote:
I was thinking it should be easy to find some $40 fan/pump that would
deliver low-pressure air from a clean air location, via hose, to a
mask.

Not so. *They all seem to want many hundreds of dollars.

What gives? *I'm not asking suck air through a garden hose, but this
doesn't seem like a big feat of engineering. *I don't even need HEPA
filters.

Every 33ft of (fresh) water is 14.7lbs...so you need a huge volume
(cu.ft) at around 40lbs constant.