Sh4dowAlso have a ski shop guy adjust your bindings. Even if the boots seem to fit, if the forward pressure is off the skis will not release in a crash regardless of if your DIN is set right. Bring a boot and your skis to a ski shop and have the bindings adjusted. If they need to be redrilled that will cost $30-$60 depending on the shop, if they do not need to be redrilled (if the previous owner had boots of the same or a similar size they can be slightly adjusted without redrilling) then it should be really cheap.
Better still take your skis when you buy boots and the shop should adjust for free if you are buying boots. You may not get a remount for free but some shops will do it for free if to buy boots.
If you don't have skis at the time you get boots consider buying in that shop too. You will often get a very good deal if to buy a full setup and they will set it all up for you usually for ftee as you are buying everything there.