Right now these can usually be had for free or at very little cost, because most people that have them are moving to the small satellite dishes. I got mine from a neighbor of a co-worker. There are a few modifications that have to be made to a C-Band dish before it can be used for radio astronomy. In other words, I let the earth rotate underneath the heavens to bring an object into view. None of the other electronics that came with the satellite dish was usable because it is set up for a different frequency range than what I wanted to monitor and the electronics just aren't sensitive enough to listen for weak signals from interstellar space.
Radio telescopes are similar to optical telescopes in that they are photon collectors.
However, radio waves are much longer than the waves of visible light. So it takes an object about 16 minutes to drift across the field of view. There are several different electrical components that are located right at the satellite dish. We can call these the front-end electronics. My system is a classic prime focus radio telescope.