Stepdown transformers come up often. There was one on Amazon I linked to a few pages back that seems to be a fan favorite.
Stick with the adjustable screen stems/GonGs, IMO. The fixed glass work fine, and some like them. But, an adjustable screen is key to get the most out of your nano. Having the ability to adjust your heat is a little more important, but having the ability to adjust the distance to heater in the stem (with adj screen) allows you to tweak to find your favorite set up. It's not too hard to find your own perfect distance and repeat it, and you also have the ability to tweak this way or that depending on your material, what kind of buzz or flavor you're looking for, whatever glass, setting a little different for visitors, your mood, etc. They're also a lot easier to clean and maintain.
A clean screen makes a big difference, so pick up some extras with your order. While it's good to keep your glass stem/GonG clean also, a quick screen switch out will keep you rolling. I usually switch screens 5 or 6 times between glass cleanings. I have a bunch of them and keep the dirtys in one container and the cleans in another. Every month or so I clean all the dirty ones at the same time and replenish the clean jar. Just soak in alcohol for an hour or two, give a quick scrub with an old toothbrush, rinse and dry. Pretty simple!
Agree with
@CarolKing to go with 18mm. Most glass that pairs well with nano is 18mm, and adapters can make it work with 14mm if you happen to pick one up.
One other thing to consider since it seems you'll be ordering in a few weeks... What kind of wood? I have an exotic, a walnut and my deer old Cherry Girl (almost 4 years old and still going strong). I've also used a few different maple and cherry nanos. There is very little difference in performance, if any, from wood to wood. But, nano envy can get to you after a while. If you stop by here often, and many do after they get a nano because of all the GREAT people that participate in this thread, you may find yourself yearning for something a little nicer than you purchased when pictures pop up. Budget & personal preferences both come into play here, and I'd suggest you go with your preference if you can swing it. Don't get me wrong.... even the plain old maple is a beautiful piece of wood. But when you're sitting there stoned, the prettier ones are more fun to gaze at. If your budget allows I'd suggest you check out
@Snappo 's exotic woods. You purchase wood separately from him, and he will ship directly to Epic. Just be sure to pick something that is sized properly for nano. Once your wood gets to Epic, customs don't usually take too long to be completed. Epic usually has some nice exotics available too. Snappo's wood thread is
here.
My lovely Amboyna Burl exotic with wood from Snappo. Pic is 3 months old and those cracks look exactly the same. Think they're just part of the wood. They're actually hard to see if not in the sun and in a close up shot.