The respirators listed at $140 are actually a case of 12x50pc.   That's a tota of 600 respirators for $140.  (Original price).  I'd say that is reasonable.
Now, marked down to 600 respirators for $7.65 -- I'd say that is the best price you'll ever dream of finding!
Anyhow, who needs 600, right?  they carry a 1x50pc for $1.28  which is what I got  (among other goodies!)