it sort of comes down to HOW COOL you need to look
there are tons of good gear that isn;'t SNOWMOBILE targeted and can work just fine and maybe you already even have some!
the most specific snowmobile item you will need will be a helmet
and this also is a question on price, as they range from cheaper to HIGH, all depending on what you feel you mneed most
MX style and goggles, , or heatedshield
ME, I prefer a heated shield helmet and a modular at that, I find it works best for ME< but this will be something that depends a LOT on where and HOW you ride!
so you have to ask a lot of honest questions about what you/how and where your riding!
but a decent helmet set up can be cheap or HIGH pending what YOU want!(close outs ion helmets are always cheaper to buy, but some times you cannot return close outs so be careful, as IMO< as of the last decade or so, it seems helmet makers sizes vary a LOT from what they used to, they all seem to run smaller now??)
as for gear, like jackets, pants/bibs and so on again, close outs can be your friend on saving $$
but I have used and worn things NON snowmobile related and worked JUST fine, I have a CAT( Caterpillar branded work jacket that I wore for 3 yrs and LOVED it, was wind proof, warm and had a Zillion pockets that safely held things, cost me like 99 bucks at a local Sporting good store and wore in in temps down to minus 30) Still have jacket too and its held up fine to a lot of abuse!
But when dealing with snowmobile gear or things you can wear when riding, it just has to be IMO< wind proof and of decent insulation, water proof is nice, but NOT always needed, most things wind proof have decent water resistance to them
and you can always look at HUNTING gear if no snowmobile shops near you that carry clothing, as much of it is also made to the same specs and designs, just NOT colors to match sleds!
SO< like I said, odds are you may already have some gear that will work just fine
advantages of BETTER snowmobile(or even hunting gear) is they have more venting, to help you cool off, but many folks get by just fine on gear that isn;t top shelf, or most costly
some times its best to ride a first yr in lesser gear and find out what you WANT in better gear, plus along the trails there are many time SHOPS that sell gear , you THEN can try on and remember things and at end of season, odds are NEW gear will come out and that older stuff will end up in close outs, on many online larger stores!
and also, keep in mind, that NOT all folks handle cold the same, so what works for ME or someone else, may NOT be what works for you!
decent layers of gear are a way to start, get some decent base layers you can remove or add, as needed along the trail, a good bag on a sled can carry quite a bit these days
you DON"T have to be super cool looking to enjoy this sport or spend a ton on gear, just try and keep all your outer layer windproof, as wind/windchill is what tends to get most folks cold
all them tiny windscreens sleds have to make them look COOL< do NOTHING to help keep a rider warm, if your not a cold hearty person, investing in a taller windscreen is money well spent, over buying higher costing gear IMO
another tip, you can try, is join a snowmobile club and since most have facebook pages or web sites, and place a add asking if any have any gear they wish to sell, then you an get some deals maybe on good gear, slightly used, as a LOT of guys buy gear often and have extra s laying about they don't use anymore!m, OR want to upgrade,so, asking never hurts and might save you some $$$