Monitors

Dear Logan and Tek Syndicate crew,

At the moment I have a 21.5" acer monitor (It's 1920x1080 obviously) and a really old hp f1523 4:3 15" monitors. I would mount my acer on a monitor arm, however it doesn't  have any visa mounts:// So, it is my birthday and Idk weather I should get two acer 24" monitors and an arm for them (That would be like £290) or just get another acer monitor and mount it vertically with my other two monitors (Baring in mind that I would love to mount a monitor vertically). However, if I just get one, they it would be bigger than my main 21.5" monitor so it seams a bit of a waste. Can anyone maybe think of a creative, good way to mount a non visa monitor vertically, or just possibly recomend a few cheap 1080p monitors (I don't really wanna break the bank though). Ohh, also, my desk is only 112cm so it's not massive.

Thanks, Dan