Want to build yourself a radio telescope? The Society of Amateur Radio Astronomers has a rich catalog of tutorials to build them on the cheap.
Of particular interest are instructions to create an “Itty Bitty Radio Telescope” out of a TV Satellite dish, as well as VLF radio reciever kits for $120.
And since we like it so much, here’s another resource for the Itty Bitty Radio Telescope with a lot more links and a video demonstration.