I bought Bosch Mirco Edge wipers at AutoZone. It has been a little while now, so I don't recall if they sell just the refills or not.
Just checked out their website for it:
BOSCH
MICRO EDGE 43320 $5.99
FITS EITHER SIDE
BOSCH REFILLS INTENDED TO FIT BOSCH WIPER BLADES ONLY.
It also has a symbol that it is special order though.
One thing which I always use is Rain-X. Apply it every time I wax my car or maybe a couple times between waxes depending on how much I use the wipers. It is superb at sheating off water at any speeds over 40mph. In a huge downpour you never have the problem of not being able to see. In the winter it limits the adhesion ice has on your windshield. It also reduces friction on the wipers which make them last longer. However it will make your wipers streak a little bit all of the time. Also don't use the washer fluid kind, I've heard of that damaging paint, do the direct application.