As a flat-footed person who wears orthotics daily, I understand the value of custom footbeds for skiing. However, the continuing saga of my own "custom" footbeds has taught me that few proclaimed "boot fitters" (read "kid working at the ski shop") possess the knowledge to acurately address the individual and unique needs of each skier. Hell, the last two podiatrists who made my daily orthotics couldn't correctly assess my needs.
Fortunately, I finally met a true boot-fitter (Jim Mates) who, within 2 minutes of looking at my feet, indicated that I have Morton's Toe (http://www.mortonstoe.com/), and that I probably have a tough time with balance. (Speechless). He stuck his hand under the ball and big toe area of my foot while I stood on my current orthotics to make the point. (More speechless).
Jim also took a look at my wife's height, body shape, bone lengths, and foot shape and rambled off three potential issues that she might encounter while skiing. She practically teared up. Just prior to meeting Jim that morning, she had asked if I would be sad if she gave up learning to ski. When asked why, she replied, "it hurts to ski."
Three years and four "boot-fitters" later, I finally feel like skiing will be the fun family activity that I always imagined.
GET THE FOOTBEDS, BUT DO THE RESEARCH!