Just thought I'd chuck this in here because I see quite a lot of threads about people with foot pain and when people suggest footbeds they're like "yeah, maybe I'll try some".
Pretty much everybody should get footbeds.
The reason for this is that most boots don't actually come with a proper insole. From my experience the higher-end the boot, the less of an insole it will come with. For those of you skiing decent boots without footbeds, go pull the insole out. I bet it's a flat piece of cardboardy fabric about 3mm thick. The manufacturers just chuck them in there so you have something to try the boot on with (if you don't take your footbeds to fittings). I guess they assume you'll get/have a proper insole anyway, if you're buying expensive boots.
The ones that come in the boots provide nil support for your arches so when you're putting pressure on your foot it becomes flatter, longer and wider. This is why your foot feels squashed from the sides or on the toes when you ski despite the fact that it felt great in the shop.
Likewise they have almost no heel cup so your foot can slop around in the back of the boot, reducing control and energy transfer.
In my opinion a good footbed is one of the best investments in your equipment you can make. You'll ski better and in more comfort. You may get away with some $10 replacement insoles from a shoe store but really you should be spending the money and getting a pair of custom molded ones. The difference is just unreal.
TL;DR: Get footbeds already.