This is for heavy screens.
I don't think it's been any cheaper than this.
Heavy Duty Compatible: The monitor arm is suitable for mounting most HEAVY large screens 24" - 42" in size and 2-15kg weight and is compatible with 75 x 75 mm and 100 x 100 mm VESA. Suitable for heavy-duty computer and gaming monitors.
Fully Adjustable: Newly designed Head Units - Tilt angles +12° to -12°, Swivel angles ±90°and 360° Rotation, Max upright lift 435mm and max extension up to 695mm. Four different installation directions are available according to actual needs. Fully adjustable to ensure your comfort.
Sturdy & Stable Construction: Arm stand with both C-Clamp mounting and Grommet Mounting are available. Made of top-quality steel and aluminum alloys, heavy-duty construction keeps your arm mount stable.
Ergonomics Design: Improve your overall well being by creating the most comfortable viewing angle for work or gaming - Enjoy the freedom to adjust your monitor height and angle
Installations: Comes with detailed instructions and all the necessary hardware, Please DON'T adjust the tension screw without the monitor mounted on it. The outside measurement of the VESA Plate of this product is 118*118mm, so please check the recess size if your monitor has a recessed VESA Mount. Please also pay special attention to the size of VESA Plate if your monitor is curved or your VESA hole is inside a recession area.
NB45 Single Monitor Arm Installation video
Also a half-dozen other reduced (but not cheapest ever) mounts available.
Cheers bought