I bought my pair from an orthopedic shop.  Most flip flops have zero support for your feet.  Especially for those with flat feet like myself.  These are great for casual/sporty wear.  Now if only they would come up with dressier ones....

I have very flat arches and wide feet.  These are both comfortable and supportive.  Another brand to look out for is Olukai which make nice quality, supportive, leather flip flops.