DROP + HIFIMAN HE-35X Over-Ear Open-Back Headphones, Gray $96.46 Delivered @ Amazon AU

Not planar driver as listed in the title on the Amazon page - they have 50mm dynamic drivers instead.
Lowest price in the past 2.5 years according to CamelCamelCamel, previously priced usually around $220-$230, looks like they have started clearing them out since around Aug - Sept last year.

The Drop x HIFIMAN HE-35X delivers true audiophile performance at an entry-level price. It features the same 50-millimeter dynamic drivers developed for the HE-350 and has been retuned for an improved frequency response. Using an electrical high-pass filtering circuit in each ear cup, we’ve balanced the treble for a smoother overall sound. This model is a whole lot more comfortable, too, with the same angled hybrid pads—a combination of velour and breathable synthetic leather—found on the HE-400i. The yoke is reinforced with an internal metal structure for added strength, and the cup connectors are more durable with a larger 3.5-millimeter plug size.

Product page:
https://drop.com/buy/drop-hifiman-he-35x-headphones

Specs:
SPECS
Drop + HIFIMAN
Operating principle: Open back
Driver: 50mm dynamic
Impedance: 19 ohms
Sensitivity: 98 dB at 1 mW
Frequency response: 20 Hz–20 kHz
Premium angled hybrid ear pads
Cable: 59 in (150 cm), detachable
Cup connectors: ⅛ in (3.5 mm)
Plug: ⅛ in (3.5 mm)
Weight with cable: 13.6 oz (385 g)
Weight without cable: 11.6 oz (330 g)

See following links for reviews and measurements:
https://www.head-fi.org/showcase/massdrop-x-hifiman-he-35x.2…
https://diyaudioheaven.wordpress.com/headphones/measurements…