Over on our Facebook page member Александр has let us know about a Russian amateur astronomer, Alex who has been using the RTL-SDR for radio astronomy. Alex uses an Elonics E4000 RTL-SDR combined with a 3.7m mesh parabola dish with 1420 MHz waveguide.
At the center of his system is an LNA with 40dB gain and a very low noise figure of 0.2dB. This LNA appears to be based on G4DDK’s VLNA, but modified to work with the 1420 MHz frequency used for radio astronomy. It seems the LNA can be ordered for 140 USD from the above link.
Note: The above Russian links are machine translated with Google to English.