Wow, that's a tough question. While I'm sure there are other programs at about the same price point as n-track, and probably some free ones, I don't know of anything that even comes close to n-track in quality anywhere near its price.
I'm curious, too. If there are any programs that match your desciption I don't know what they are.
Well, I know Cool Edit 2000 is pretty close in price, but for multitracking it sucks. Isn't there also a program by Cakewalk, like HS2002 or something? I think it's under $100 but it doesn't support VST which I found to be a major turnoff.
I've only seen ONE free multitracker, and it didn't work
I now this great program which is called Internet tape deck, its totally free and you get really good soundquality, without having any expensive gear at all!
It used to be available at http://www.recordlab.com/
I dont think it is anymore though...search through the internet and you will find it, otherwise ill give it to you, its a 10mb file.