RPG Advice #1: The Desert of Doom

I'm in a bunch of Facebook groups where people talk about the various tabletop rpgs they're involved in. Sometimes they ask for advice on what to do next, or on characters or whatever. Every so often, one of these questions will tickle the creative spark in the back of my noggin and I'll usually write something far too damn long and elaborate which might get a like or two but then fall into the void never to be seen again.

Today's situation is as follows: 

My players screwed up, badly. They had the choice to use traditional travel methods to get to a city they’ve never been before, or teleport there via a spell without having knowledge of a teleportation circle. They chose teleportation. The one casting rolled badly, they took their damage and are now separated miles apart about 100 miles from where they wanted to go.

Here’s the real problem. I informed them before they chose to teleport that the city they were trying to get to was an oasis inside of a desert that in the past was effectively glassed by a god. Over thousands of years, erosion turned the glass to fine sand that will rip your lungs apart if you breath it in. So now I’ve got them separated, alone in the middle of this killer desert and need a series of encounters to bring them back together. Any thoughts?

                                                                                              Art by Tuomas Korpi

* One could be rescued by a caravan of Bedouin-style tribesmen who have developed techniques of making their way safely through the desert between oases.

* One could be desperately searching for shelter when they fall into a series of tunnels used by a race of subterranean insect people.

* One could happen across an ancient ruin almost entirely buried beneath the shifting sands, discovering strange inscriptions, ancient scrolls and maybe a weird artefact or two. The ruin should of course also feature traps, ancient magical/mechanical guardians or ghosts/undead.

If you don't feel like running three entirely separate adventures with a split party, you could handwave a lot of the detail.
"You were rescued by a group of tribesmen. You don't recall much, as they had you stuffed inside a kind of shelter made from the shell of an immense beetle most of the time. You couldn't understand 90% of what they said to you, but definitely got the impression they were unhappy with taking on someone who would be a drain on their supplies of food and water.
Erase off (x)gp worth of supplies from your equipment, representing what you gave them in exchange for your passage. By the end of the journey, however, you'd done something to distinguish yourself (Get the player to suggest what that might have been), and they gave you a medallion you can wear on a leather thong around your neck. Should you ever need something (it shouldn't be something that represents more than a moderate inconvenience), find a member of the Tribe, tell them this word and show them the Medallion."

Come up with something like that for the other players, where if they want to explore the side-quests more deeply later, they can but you don't have to do it right now, "I couldn't spent TOO much time exploring the ruins because I was running low on water and that had to be my priority!"
Take something off them because they DID screw up and that should cost them something, and give them something minor that could lead to future possible adventures.