My radio was a little over $100 at Fry's last week. I think it was on sale too.
It's like the SA thread pointed out though... if you get one, you want to get one you can tune 1khz at a time on the shortwave bands... you also want an input for an external antenna. I'm going to start hitting up thrift stores soon because they are supposed to be a good place to find decent equipment for really cheap. I'll also probably hit up the local library for some antenna theory books and whatnot... 99% of this shit is stuff that I don't even understand.
But yeah, Nach is right... you could pretty easily build one of these things if you knew what you were doing. My problem is that my understanding of all this shit is pretty rudimentary, so I have no idea if I'm improving my experience by, say, draping 65 feet of speaker wire all over my deck outside my apartment and flinging cables onto the roof.