Please keep in mind that the required gear is a minimum amount of gear that should be carried.  In the extreme conditions of the event, a small injury can quickly turn into a life or death survival situation.  Be prepared!  Don't skimp on your gear!

Check out these options...

Emergency Bivy --
$30 - S.O.L. Emergency Bivy
This is a good emergency bivy by a reputable and proven company.  It costs a few bucks more than some of the more generic options.
$10 - Generic 2-Pack
I cannot vouch for the brand, but this is a cheaper option that would qualify

Headlamp --
$70 - LED Lenser MH10
I have had this headlamp for a few years and LOVE it!  It is super bright when you need it to be but can also really dim down. I use it for Search and Rescue and a number of team members have purchased one as well after seeing mine.  You can also charge it on a USB battery pack if needed.  

First Aid, Whistle, Fire Starter, Emergency Blanket -- 
$15 - S.O.L. Waterproof Survival Medic First Aid Kit
This kit covers FOUR items from the gear list (Whistle, fire starter, first aid kit, emergency blanket).  I would, however, suggest supplimenting the first aid kit with more items as this one is VERY minimal.  Also, please ensure your whistle is attached to the outside of your pack.

Flasher(s) --
$13 - Emergency Flasher (2-pack)
Here is an example of what would qualify as a flasher for the event.

4-Season Bivy (extreme weather) --
$180 - Outdoor Research Helium Bivy
There are cheaper options, but you will be hard pressed to find a bivy that is more versitile and light.  I have personally tested this bivy in very extreme conditions and it has held up wonderfully to rain, hail, snow, and wind.

Charging Pack (extreme weather) --
$11 - 5000mAh Battery
Since this is only a 5000mAh, I would recommend getting a couple if you go this route.  The reason I picked this one is because of the smaller size so it can be stashed comfortably in more places.  Remember that cold will drain a battery FAST!  Best to have a backup that is close to the body to maintain the heat.

Sleeping Bag (extreme weather) --
$350 - Marmot Ouray
There are a LOT OF OPTIONS in this space.  Your trade off will be packable size, weight, and warmth.  I am suggesting the Marmot because I have had my Marmot sleeping back for 20 years and it is AWESOME!  It is light, packs small, and is still warm after all that time.   I highly recommend biting the bullet and picking up something nice.

Disclaimer:  I have linked these items to our Amazon affiliate account, so Fat Otter Adventure Sports will receive a small commission if items are purchased through these links.  You may be able to find these items elsewhere for a lower price.