As you stated, that you want to run a sand blaster, and tat requires a
fair amount of "cfm"-cubic feet/minute, which means a large compressor.
I am a field service tech for Atlas Copco air compressors, capacity
and quietness generally (in less expensive air compressors) do not go
together, if price is important than a exterior location with sound
deadening material is the answer, however if you have the money or that,
and can afford to put some more with it then I would suggest looking
into a Atlas Copco oil free scroll (SF2) compressor, as I have serviced
many located in quiet work areas in a lab at "Shrinners Hospital in
Boston MA", at many "Lens Crafters" locations.
I'm not sure of there cost, I would guess around 4 to 5 thousand, they
are available in single phase (220-230) volts as well as the
commercially normal 3 phase (208/230-460) volt.
Expensive but very quiet, just about as big as a dormitory
refrigerator and not as loud as a pain shaker.