If you know someone in the hvac biz, or salvage, you can save a couple
hundred
bucks, if you need an overall room dust filter. Aquire an old
heater/AC blower, mount in plywood box behind a filter arrangement.
Hang from ceiling. I've seen plans online you could probably google.
IIRC, you use several filters in series.
I've also reaseached using 1 micron filters with such a setup, but the
price of the filters makes it cheaper to buy the whole unit already
built.
Also, I've heard it's a good idea to have a time delay switch, so when
you leave your shop for the day, the filter continues to clean the air
for awhile, letting less dust settle.

==============
Both of my sons are HVAC Contractors...and I got my squirrle cage
blowers for free...so I made a few filters ..plus I purchased a Delta
Air cleaner prior to making a few of my own... The home made ones
work about 90 percent as good as the Delta... without using any of the
expensive bag filters... just plain old furnace filters...

I am NOT interested in protecting my Lungs in the workshop... BUT I
enjoy working in a clean place...and if a clean place is better for my
health it is a bonus I will accept...

\My comment on the home made ones working almost as good as the Delta
ONLY is made frrom the amount of "dust" that accumulates on the
filters in a given period of time... The reallity is that the Delta
with its bag filter does remove the really small stuff better..BUT
when I open the door to the shop in the morning I do not have any
layer of dust on the table saws top etc... That is good enough for
me...

The timers are EXTREMELY Important...mine run 2 hours after I turn off
the lights...

Bob Griffiths