I have been experimenting with an USB receiver stick originally made to receive DAB/DAB+ broadcast. It is based on the Realtek 2832U complex demodulator IC and has the Elonics E4000 tuner IC.
Installation details as per G4ASR/G3WER info above. I use SDRSharp software. I am pleasantly surprised by the frequency accuracy, any offset can be corrected for in software. Initially the screen was a bit jerky, I believe the software is CPU hungry or it is the way the graphics are inplemented. I use a P4 3GHz machine. I find that resizing the application window to 'frequency span' only (i.e. no waterfall) helps.
On 70MHz I could receive signals down to -115dBm, or S2. A bit low for NBFM to decode, however, at -109dBm (S3) it was already much better. Beacons/CW signals were decoded at -115dBm, even into the noise level playing with the software filter settings.
So if you are interested in 4m and want to check out local signals this is a cheap way to start out!
The WFM setting allows to decode those OIRT signals during sporadic-E.
Another USB receiver stick using the R820T tuner IC will give frequency coverage from 24MHz to 1766MHz, so even 10m and 6m for cross band are within reach.
73, Phil ON4TA