I have had two Snap-Dry boot driers, for about 10 years. My first one gave up the ghost two years ago, probably because of user error on my part. I have used in the car (I have 12V to AC 120 adapter) coming back from the mountain.
When I get back to my condo, the first thing I do is to put the Snap-Dry in my boots - 8-12 hours - and however wet and stinky my liners are, they are dry as a bone the next morning.
I think Hotronics (same company makes an in-the-boot heater while you're skliing) bought Snap-Dry. Often, I take my liners out of my shells (I sweat a lot) and use the Snap-Dry on only the liners. I made a point to carry two new ski socks all the time, in case I want to change socks, but that only happens in not-so-cold weather, say in the Spring or late Spring.
One other thing if you don't have boot drier, is to stuff a lot of newpaper in your ski boots. Get it all in, near your toes and your lower liner (enclosed with your foot). It works.
But as for buying an expensive boot drier, last year's new skis are that price.