I finally took their advice, because I wanted to eliminate any external impediment to improving my skiing. I wanted to be sure that if I was doing something wrong, the only thing causing the problem was me. As one instructor put it Mike, blame the bus driver, not the bus.
You can find a number of shops near ski resorts that can make reliable custom foot beds. Prices range from about $40 for precut beds to $200 or more, depending on precision, material, and labor. In general you get what you pay for. I chose to use a Surefoot.com shop, run by manager Ray Rice, for my foot beds. Surefoot has over twenty shops in the U.S., Canada, and Europe, comes highly praised, and the guarantee of their product and work is honored at any of the stores.