I called out to RC/LB because y’all seem to have the most knowledge about audio peripherals judging by some of your posts. Certainly anybody is welcome to chime in. Long story short, I’m shopping for a decent yet inexpensive set of wired headphones to use with my father’s old “Treasure Hunter” metal detector. It takes an old style fat jack (sorry, not sure the technical nomenclature), but I have adapters for the smaller jacks. I’ve been buying throwaway Brawlmart sets for years, but it’s getting tedious. Occasionally I’ll use them with my Samsung 10 something phone (not a fan of Bluetooth). Budget is $30 shipped. Amazon is preferred as I need something by Columbus Day. I’ve looked, but don’t know squat about these things.
’Oo, me?
Unno. “Fat jack” likely is for a ¼” phone-plug. Plenty of adapters for that…
Buncha cheap MPOWs and such on vipon every now and again.
No idea what you want/need, whether on-ear or over-the-ear, hear-through vs noise-cancelling, etc.
No idea if yours have to be earmuffs, or if earbugs can work, too.
So… narrow it down some. 
mine uses the “fat jack”, too, and i also have the smaller adapter.
i have used Craig’s List for my headphones.
here is a Boston Beats example for $10:
https://boston.craigslist.org/bmw/ele/d/needham-heights-beats-by-dre/7369416989.html
Sorry…earmuff type. The ones I’ve been using are just junky foam covered jobbies. Noise canceling is not critical, just need something that will minimize ambient noise.
Thank you for responding.
Oh, then one of those cheepcheepcheep MPOWs should work fine.
Keep looking through vipon, unless you need one, like, Right Now.
I prefer light, heap headphones like this:
I can hear someone sneaking on me 
Excuse my ignorance, never used CL. Are those “used”? Do they cover the ear?
Your hearing is better than mine, brother. I’d need side view mirrors attached to thwart a sneak attack. 
As soon as I figure out what MPOW is, I’ll be looking. Thanks.
MPOW is under a different name now on Amazon. RC knows what it is.
Edit- here it is
Mpow is probably your best bet, and then just get one of those .25" to .125" adapters.
Mpow got banned from Amazon, so you need to look for rebranded Mpow headphones.
Looks like there's just one on sale right now--see pennzy's post above.
If you check some of my recent posts in this thread, there are a couple more rebranded Mpow headphones that I know of, but they're not on sale right now:
Thanks!!!
1. Are those “used”?
yes.
however, some listed are new.
CL is an online Flea Market,
or garage/yard sale.
2. Do they cover the ear?
these do not cover completely.
others do.
this was just an example
of one set available
out of many.
Make sure you get a wired headphone with the length of the cable that you will need for your purpose. Some people need long headphone cables but unfortunately, most headphones come with cables too short. 
If you are in the U of S, Monoprice headphones have a very good reputation on budget forums like head-fi.org
Here are some examples:
Any headphones will do just make sure they are comfy. More important is a heavy duty spiral cable. But if you try wireless systems like XP have you wont go back to cables no way.
Here's another rebranded Mpow:
https://budgetlightforum.com/t/-/29803/4499
Also, here's some good looking bluetooth headphones on sale:
https://www.amazon.com/dp/B08MJV4X7R
https://www.amazon.com/dp/B08R684SDG
And I have never owned any Monoprice headphones, but I have heard good things about them on head-fi.org (like sochi111 mentioned.)
Having spent a bunch of time behind slow and fast sweep detectors… delay in your headset will drive you to frustration! I only use Gray Ghost headphones. With my MineLab slow sweep it is critical to here the quick tones for silver, and they are so close to iron pop off that I rely on good tone separation. With my fast sweep Teknetics and Whites units if there is any delay, you may be 3 feet away from the target by the time you get a good tone.