The "perfect pixel" is available for several models of the Catleap, rather than being a separate model itself, and as far as I can tell, it increases the price because the monitor is pre-inspected for defective pixels, and only models free of bad pixels qualify. The non-perfect-pixel models can sometimes arrive with no dead pixels, but at that resolution, a few defective pixels in the outer regions can be hard to notice unless you specifically look for them. The SE models lack speakers (though I wouldn't expect much from the models that have them), and the MULTI model has HDMI and VGA inputs in addition to dual-link DVI, so it's only worthwhile if you want to hook up additional sources like an XBox 360 or PS3. I've read that the tempered glass models are only worthwhile if you have children throwing things at the monitor, making you look for extra durability (there might be other reasons for the tempered glass, but I haven't noticed them). I think all models of the Catleap have glossy panels, so if you have a brightly lit area to use it in, you might want to look for an anti-glare screen protector to put over it.
It's true that 2560x1440 monitors from Dell, Apple, LG, etc. are usually $700 or more, but there are other lesser-known brands from South Korea you can get on eBay, such as Achieva and CrossOver.