More or less having just gone through this myself right now here is my two cents worth.
A couple things you have to remember.
: At the beginning of the season you will find a huge selection of boots and a full range of sizes available at a premium price. People need boots and are sucked into spending the money at the start of the season.
: New designs on boots, (skis bindings, etc..) are generally introduced to the distributors around Christmas time for the following ski season.
: Distributors usually place there orders in the late winter early spring. Sporting/skiing outlets usually place there orders mid spring to the first of summer for the following season.
So taking all that into account you have to realize that the last thing anyone wants is a boat load of product on there shelf at the end of the season.
The key is figure out the type of boot your interested in, ie competition, advanced, soft, etc... and match up information on forums like this from others, on boots that will fit your foot and skiing type. Check on manufactures and what they may have coming out new in the following year.
Once you have an idea what your looking for then its a matter of going out and finding them and then trying them on. I don't necessarily believe in buying on the spot unless the shop is willing to cut you a serious deal and/or throw in custom orthodics and boot fitting. The best thing is to find what fits you and then go on the net and see if you can find it at a better price.
The higher end the boot the harder its going to be to find at the end of the season. I just went through this with the Tecnica Diablo line.
Tecnica was replacing my exploding TNT Race Pro's with any boot of my choice. So I posted a couple of questions on some forums read loads of information and narrowed it down to the Diablo Race Pro or the Magnesium. Then I went out and tried to find them. Turns out that these two boots were not available anywere in Southern California in March, and I called about 50 shops. The one place that had even carried the Magnesium or the Race Pro line only had one pair, Mags, in the wrong size. I then got on the phone and called a couple of the speciality Ski shops in Mammoth and Tahoe, even then I could not find the boots in my size. My goal was to try them on first then let Tecnica know what I had decided. I even looked across the net and could'nt find them anywere on the west coast in my size.
I had pretty much given up until next season when I ran into an old friend who managed the ski center of a local sporting goods center. He was an old racer and knew his boots. I sat down with him, had him measure out my feet and give me his honest opinion. He had skied on both boots and had the same skiing ability as myself, and that's how I ended up getting my new boots.
Just remember that boots are the most important part of the ski equipment package. If you have good boot fitters in your area start there. If you have to travel to a resort, make sure its during the start of a season and demo out the boots your interested in. Then start a net search when you get back. Just remember the start of the season is when your going to find the big selection, the end of the season slim pickens.