If a piece of equipment is so vital to the adventure, do not make the assumption that the player will think to spend their precious starting money on it.
I put the following items in this category:
- Torches (yes, I've had the players arrive at the dungeon without any of the characters having bought torches. I just gave them some, but see below for why this isn't ideal).
- Clothing and Backpack.
- Tents, Bedrolls and Flint & Steel.
Likewise, if you handwave things like camping equipment and food, do not let players spend money on that stuff only to see everyone else get it for free.
My solution to this for Into the Odd is the new addition of this passage at the start of the equipment list.
All characters carry standard equipment, including simple clothes, a backpack, basic camping equipment, torches and a few days' rations.