Suitable companion monitors for HP LP3065 30" primary monitor

Suitable companion monitors for HP LP3065 30" primary monitor

I have an HP LP3065 30" monitor - now I want to add a couple of companion screens to either side of it - I've heard to people suggesting 21" monitors in portrait mode - but it seems difficult to find a suitable panel these day, as 22" wide-screen monitors have become common, and I can't seem to find anything with a suitable 1600 pixel width.