I wrote this quick…so up front… try to work around any bad syntax an so forth.
You’re better off at the ‘big box’ rather than buying someone’s old gear who will not take it back. Boots can be tricky to buy on your own, I recently tried to buy boots from the web but ended up sending them back. They took them all back and credited my card back (minus shipping) without hassle and I researched all ,three boots, bought all three at once from the same place, unfortunately I have a little bit odd and somewhat narrow foot (98mm), so none of them fit me, as a new boot should, to allow for later, if needed, adjustment. I strongly suggest reading the ‘boot fitting forums’ here, I know one of these guys from when I was teaching skiing and would recommend him in a second if you were down here.
You can’t go into one of those big box places without: 1) Minimum, knowing your foot size, and width on EACH foot. Is your foot wide, normal, or narrow? 2) Checking the technical information on the boots you’re looking at and writing it down and then knowing what the information means and how if effects your foot, level of skiing, and so forth. I suggest trying on at least four or more different brand of boots. You cannot rely on any information the boot seller there gives you, for that matter even someone working at a ski boot shop. With a little studying on your own and the fact that you are feeling the fit you will be better off. A good boot fitter yes, but not the salesman. After you've tried the boots...walk away, study the information on each and se if they match up to your, foot, weight, skiing, and usage.
I recently tried to buy boots from the web but ended up sending them all back. They took them back and credited my card back (minus shipping) without hassle and I researched all ,three boots, bought all three at once from the same place, unfortunately I have a little bit odd and somewhat narrow foot (98mm), so none of them fit me, as a new boot should, to allow for later, if needed, adjustment. As I said earlier, I was PSIA ski instructor and even with my background and knowledge (such that it is – grin), I failed to find a pair of boots on my own. That isn’t to say you won’t. It’s just that for me, and the majority of us, it’s not like buying a pair of shoes.
IMO do what I did below at your store even though it's not a boot shop.
I ended up going to a good shop and trying on four more boots that they suggested, wearing each for 45 minutes to an hour, so they warmed up to really start feeling the fit then removing and ‘rest’ the feet 15 minutes between, then on to the next boot. So I tried six different pairs of boots before finding the pair that fit ME as they were supposed to. A boot fitter has an oblation to you to give you the best fit you can get, but YOU also have an obligation to him (and yourself) to do your end of it by being knowledgeable enough to pick out of the selection process a boot he can work with.