Well, the above postings are correct, but I thought maybe I would add a bit more about them. The rackmount unit is the only one of its kind and is used by virually all performers in their live rig. Cher and Kid Rock obviously use it, but I have seen it in Jewel's rig, and I think many more, but I don't want to be wrong about that. The price for the rackmount unit is 649$ at 8thstreet.com I think I have seen it cheaper than that before. Antares also makes a plugimn version. They have the TDM format, which I believe is used for Pro-tools, they have a Mackie Digital fromat, for those who have the makie digital 8.bus. and they have the direct X version (for the rest of the world). I have the direct X version and I love it. IT really makes the difference between the basement recording job and going down Nashville and stepping into EMI or something. If you are good with the autotune, no one will know you were recording at home. The plug in has two modes, graphic and auto. The auto usually leaves 'artifacts' that make the vocals get that Cher effect. Which is neat if you are going for that, but sucks otherwise. It sounds way too fake. But, you can tune the line graphically. It maps out the wave and you can zoom in and move the pith to where it is supposed to be. It will not fix it 100% because then it would sound computer generated. It fixes it and keep the inflection and vibrato of the singer. You can add additional vibrato too. It works on anyh wave files that one note at a time. Bass parts, vocals, even one note guitar solos, but many harmonies on the same track cause it to freak out. Oh, and when preparing to tune graphically, set aside lots of time, and save a backup copy of your original wave in case you mess up. We did a session this weekend and the producer spent about 6 hours tuning two minutes of four tracks, and they were really good takes. It will take us about 6 weeks to finish the twelve song album we cut on Saturday and Sunday.
Get the rackmount if you want pitch correction live, but it is way more difficult ot use for recording. Get the plugin if recording is your thing, but as far as I know, the direct x version can't be run in real time. The TDM probably can.
At least I am knowledgable about something.
MIKE