>>51085806Ehh. Try to buy used, since a good monitor arm costs a fortune (>150 USD/€).
It depends if you want full range of motion or not, gas-spring or not, which height you want (since most have a lift of 30 cm, which is not enough for tall people). In case of two monitors, you probably want less range of motion.
I got a used dataflex viewmaster (m5, m6 is standard now), so high-end stuff, for € 50 and it does everything I need it to. I have only one monitor though.