The Dell 24" monitors have quality control issues that the Apple displays don't seem to have. They're enough less expensive though that it may be worth it to you to risk the occasional banding or backlight failures.

Or you may just want/need analog inputs that the Apple display can't give you.

Series A03 and above of the Dell 24 inch monitor, shipping since September, have no banding issues. The monitor is absolutely awesome. The best part is you can probably keep it around for 5 years or more, and it has all the TV inputs except HDMI that you may need (no tuner, but many devices have a tuner these days.) I got mine for about $540 after a 25% coupon as part of a new computer system. You can buy some 17 inch monitors for $200 but you will definitely get rid of them in two years. Why not buy something you can keep for a long time? When you're a huge billion-dollar company in a few years from now, and want to get a 30inch monitor (the only real alternative) instead, you can simply use this monitor as a TV screen on the wall behind the receptionist. :) Gotta plan ahead for that...

And, it even has a card reader and USB ports built-in to the side. It also supports VGA on one button, and DVI on another. You can easily swap what you're looking at by connecting to two different computers at the same time. Then, simply get a wireless keyboard and mouse, and plug the USB receiver into its stand for the main, DVI, computer, or unplug the receiver and plug it into the monitor, for the VGA connected computer, and click a button on the monitor to go to the VGA computer. No KVM switch needed. Just connect to the monitor's USB/card reader cord to the USB port of the VGA computer.

I should add, the key word was 'budget' - a 24" iMac will probably serve you better (unless you need serious graphics card power or multiple hard drives).