If we decided to rank the things heard most in our store, the statement "I'll get that in (my mission), they have things more suited for (my mission)" has to be one of the top five at least.
Particularly having a base of operations in Arizona, people seem to think that because we live in such a hot climate, we can't possibly know about cold climates or outerwear that would be appropriate for the various missions of the world. This line of thinking works pretty well when shopping in a regular department store or chain store, because it makes sense. Why would a store stock a heavy overcoat or heavyweight winter boots in a place where the average temperature is in the 70s or 80s?
If you're a regular department store, you wouldn't. However, as a retailer that specializes in sending out LDS missionaries, you absolutely would.
For example, in Pomeroy's we stock coats made by a company that is based in Washington, winter socks made by a company that makes them in Canada, and scarves, winter hats, gloves and ear bands by a company operating out of New York City. These are not items made for Arizona boys. Well, I take that back. They are made for Arizona boys that are serving in Northern Europe, Ukraine, Idaho, Minnesota, and practically anywhere where ice driving is a necessary skill. We have sales staff that have served in 0F to -70F degree climates and they can attest to our winter gear. It works.
Another reason someone might want to reconsider waiting until they get into the field to purchase certain items is that you don't know where your first area is going to be. Say you are called to serve in Pocatello, Idaho. (It's a very common mission for Arizona based missionaries to go.) Well if your first area is the actual city of Pocatello, then you are probably in luck, they have stores that can get you warm clothing.
However, the large majority of missionaries called to serve in the Pocatello Idaho Mission never serve in Pocatello.They serve in one of the dozens of small towns where the largest store is the corner market. That means no access to any winter gear outside of what you can borrow until you go to zone conference or get transferred, meaning you're freezing your tail off for possibly weeks before you can get to a store. Not ideal.
As any seasoned cold weather individual can tell you the key to keeping warm isn't a huge thick coat and huge snow boots, but a system of layers. When you are properly outfitted for winter, you will have as many as six or seven layers of clothing to customize your warmth day by day. On the coldest days you'll have your undergarments, thermals over those, white shirt over that, sweater over that, suit coat over the sweater, and a dual layer jacket over everything else! You may look like the Stay-Puft Marshmallow Man, but you'll be warm even in sub-zero temperatures.
Buying a heavy coat may seem like a good idea and many mission presidents will suggest buying a heavy down coat in their area, but what will you do for the other nine months of the year when the heavy down coat is too hot to wear but it's still cold outside? That's where your layers come into play. If you've got the six or seven layers, and it gets warm... just peel a layer or two off and you're back to being toasty but not too toasty.
Just remember the old Boy Scout Motto: Be Prepared and take what you can with you. Don't plan on purchasing essentials out in the field, because you may not be in an area where you can do so. Purchase souvenirs or a nice new suit in your last area to go home in, but take what you need with you.