depends on what u want to conceal.
I like Ettusais's medicated concealer for acne. It helps to make
the pimple ripe faster and yet blend easily. I remember around $20
or so.
another concealer (but not medicated) is ice-cream concealer. Can
only be found in Sasa. This one is famous among Japanese women due
to its "industrial strength". more expensive, abt $40, I think. Not
suitable for dry skin area. When it first came out, my friend
grabbed two 'coz she bought one from japan before.