Why do surface barbells with discs cost so much more than ones with balls?

Are those top ones internally threaded though?

Internally threaded ones normally about twive the price of external, but that's because they're a bit complicated to produce, and normally better quality too.

And you really should avoid externally threaded in a surface piercing.

But things with discs tend to cost a little more simply because of the rule of supply and demand. They're not a very common purchase. I just buy the discs separately (they're pretty cheap), and put the balls in my spares box, you can never have too many extras.

The top one looks like alot chaper metals too.

The ones with the disks are internally threaded and the other ones with the balls are externally threaded. The externally threaded ones are way more common and easy to make, so they can't charge as much. Internally threaded barbells are hard to find and tricky to make, so they can charge much more because people have much a hard time finding them.

Internally threaded in definetly the better one, even for the price.

Also look at the materials and see if they are different.