A really good one was the 20" ACD vs the Dell 2007WFP: same panel lower price.can you post an example?
Another one is the current 30" ACD and the Dell 3008WFP although this is not the same panel, the one in the Dell is the newer version. If you take a look at the price now it's 1799 for the ACD and 1399 for the Dell which has a newer panel and a lot more features. In cases when people have a Mac with just the mini displayport the Dell is actually the only good option since you can get a mdp-dp cable from Circuit Assembly for something like 15$.
The 24" ACD vs two Dell 24" monitors (2408WFP and U2410) is another example. The Dell monitors are almost half the price, they don't come with glass making it usable in environments with a lot of light/reflections but both monitors need the mdp-dp cable to be able to hook it up to your Mac with the mdp port on it. However, those monitors also have dvi so you can hook an older Mac to the monitor without any problems; you can't with the 24" ACD because you'll need an adapter for that (which is rare or non-existent at this time).
Those Dells are even considered to be somewhat expensive regarding some competitors such as Samsung (they both do panels and monitors, a lot of their panels are in monitors from brands like Dell, Apple, etc.). So yes, those Apple monitors can be considered overpriced, especially the 30" monitor as it is 2 years old and thus uses 2 year old technology.
If the monitor can speak displayport you only need to worry about one end of the cable: the end that goes into the Mac. Circuit Assembly and some others have such a cable. In Circuit Assembly's case you can even order different lengths: 2 meters, 3 meters, 5 meters and custom (which will take about 6 weeks). The cable from the 24" ACD is not that long, for people with a Mac Pro under their desk it's too short, they can't hook up the 24" ACD without putting the Mac Pro on their desk. The cable length is a big issue for the 24" ACD, so much that some users don't even consider it.Plus if you have a new mac, it works seamlessly with no adapters needed and I had no problems.