The human foot is not really designed for barefoot traversal over flat hard ground. Do yourself a treat and walk barefoot over grass, sand, etc. but never indoors.
Birkenstocks are pricey, but after only 2 weeks they have helped my pain greatly. I swear by them now.
Do keep in mind that Birkenstocks are really an orthopedic shoe, and thogh they are faddish now, there is a real reason to spend money on them besides style. They are very comfortable, and help eliminate pain caused by undue stress many people get from wearing shoes without propoer support.