[quote="ultra_whippet"]I totally agree with DC Runner, both with regards to podiatrists and the Five Fingers
An experienced sports physio or therapist is your best bet. There are loads of things that can contribute to flat feet, such as PTTD (google it), weak foot muscles and a forward-tilted pelvis, but it really requires a proper examination to see what the root cause of the problem is. A decent therapist should check out your whole kinetic chain, if they only look at your feet then don't bother with them.
I recently visited a chiropractor for some acupuncture and he looked at my feet and low arches as well. Instantly recommended orthotics. I declined. As with disease, sickness, health, and nutrition, I'm more inclined to solve the root of the problem instead of paying someone to give me a pill.