A 9th level casting of the spell could create up to about 112.5gp if we go with the 3.5e economy(which doesn't have this spell, anyways), or only just over 1gp going off the 5e economy(it takes about 4 gallons of seawater per lb of salt, and you can purify 90 gallons casting at 9th level).

It's really not that good. Sure if you're level 20 and use all of your spell slots on it it's a decent sum of gold... but you're also level 20. Go rob a bank or something.

https://en.m.wikipedia.org/wiki/History_of_salt

Salt was very valuable back in the day, helps preserve food, and is the only spice you could probably get your hands on. Add to that it being a magic component, and it would be even more valuable.

Get Alchemy Jug. Or 2 levels of Artificer and an infusion.

Generate 10 gallons of saltwater per day from Jug.
Get the salt out of that for the cost of 1 level 1 spell slot.

Profit? Apparently 2.5 pounds of salt based on another comment here.

The spell affects 10 gallons of water at first level, leaving you with close to a pound of salt valued at 5cp. That's not going to break the bank, ~~but assuming you spend only one 1st level slot per day every day, in a month that will earn you 1.5gp, putting you somewhere between a Modest and Comfortable lifestyle.~~ edit: turns out these prices are per day, I can't read, and I'm going to die in poverty covered in salty rags

Well? What happens next? The story was just getting good! Suddenly all the salt dried up and people are inexplicably dying, nearly a hundred a month. What is causing this? What happens now? Does the fact that the entire town is built on a demolished holy site have something to do with it? How does the PC respond?

But competitive multiplayer online games aren't canon to the Forgotten Realms

And then, since it's a trade good, you can sell it at full price to whatever lives on that plane. Though the way it's worded in 5e makes it sound like that's not necessarily true everywhere. It works better in 3.5.

These are important questions that will be asked by your players if they haven't gone there already. DMs, pay attention. Have a solid argument planned out beforehand or suffer the consequences. The thirsty, withered consequences.

Personally, I argue that Create/Destroy Water can't target a creature therefore get fucked, cast it somewhere else or pick a different spell. Why that is, scientifically? No idea. Same reason you can't Revivify a kitchen table. Logic dictates that you could turn it back into a tree, in practice nothing happens. It's A Secret To Everyone™

My table's necromancer has a homebrew staff formerly belonging to a mummy-priest that allows him to cast destroy water, and it becomes an at will spell if used on a corpes to mummify it. The demon lord of drought and the patron of mummifcation demands it.

It allows for convenient storage and transport of the corpses he ...procures...

Hmm, a body has several holes in it... it arguable is an open container, made of animal hide.

Calm down, Hama.