Are they? AFAICS ceteris paribus, monitor prices are not that different from TV prices. It's only when you want a monitor with specs better than can be found in almost any TV (>HD resolution, high-end IPS or PVA panel) that the prices get higher, for obvious reasons.
EDIT: Also, not nearly all cheap "HD" TVs actually have real 1080p panels. They accept a HD signal but internally resample it to a lower resolution, leading to an image that's obviously blurry in desktop use. With computer monitors, you know you get pixel-for-pixel the image the video card pushes out.
EDIT: Also, not nearly all cheap "HD" TVs actually have real 1080p panels. They accept a HD signal but internally resample it to a lower resolution, leading to an image that's obviously blurry in desktop use. With computer monitors, you know you get pixel-for-pixel the image the video card pushes out.