I find this as the most affordable decent gas/spring lift dual monitor stand.

Let’s start by looking at the specifications:

MONITOR STAND SBOX LCD-S024

Desktop stand for 2 monitor – SBOX
 
Screen size: 13“ – 27“ / 33 – 68 cm
Weight capacity: up to 6 kg (2 x 6 kg)
VESA: 75 x 75, 100 x 100
Tilt: ±90°
Swivel:±90°
Rotate: ±180°
Cable Management: Yes
Inside the stand is spring loaded system that 
holds the monitor in desired position

Freely Height Adjustable: Yes
Color: Black
Material: Aluminum, Steel, Plastic
Dimensions: 79 x 12,5 x 59 cm
Bar Code : 0616320533885

You can find them on Sbox website here, along with the installation manuals.

The specifications only state “spring loaded system”, but I think the spring loaded system also includes a gas strut. More on this below.

What’s inside the box ?

Gas lift or just spring loaded ?

As I’ve said, the vertical operation of the support is aided by a spring loaded system, that seems to be also aided by a gas strut. In the video below, you can hear a hiss when the support is operated on the vertical axis.

The system is designed to allow you monitors to hover at the desired position and to allow effortless position adjustment on the vertical axis.