I think the cheap Chinese ones are Superleggero copies?
The design looks pretty similar, and the ‘impossible to adjust without cutout’ system is the same
They are, but the superlegerra has a barrel adjuster on the front bolt so you can do it on non cut out saddles. I'm not sure why they don't put it on the AliExpress ones.
I got a superlegerra for my super six for £40 on eBay. They are around. 31.6 stuff tends to be cheaper though I think.