I bought this radio for $7 at the same store where I bought the nice calculator for $4. It shows some signs of having been opened before — some of the screw heads are a little damaged.
It claims to cover FM (like the more expensive Coby radio) but also several shortwave bands, audio from four TV channels, and (I think?) AM as well. So far I've only gotten reception in the FM band, but I haven't tried it outdoors or at night yet.
It has a single LED that indicates signal strength by its brightness.
On the back of the main circuit board (a single-sided printed circuit board, occupying nearly the entire radio) is the only IC, which says it's a Samsung S1A0426C02; thanks to alldatasheet.com for the data sheet, although apparently datasheets.org.uk have it too. Apparently it's an "AM/FM 1 chip radio", but Digi-Key doesn't carry it and FindChips can't find it, so I don't know how much it costs. My Google search is eager to tell me that lots of companies in China and Taiwan have it in stock, but I'd have to request a quote, which sounds like more work than I have time for at the moment.
I initially thought the holes through the main board to something adjustable with a screwdriver were for adjusting trimpots, but they seem to be the bottom of the tuning element — presumably an adjustable capacitor.
The big coil of wire with a ferrite core is a ferrite-bar magnetic loop antenna for the longer wavelengths. It's not practical to use a simple quarter-wavelength whip antenna, like the FM antenna that sticks out the top by about a meter, for wavelengths over a few meters long. The 530kHz AM signal has a 565-meter wavelength, so instead the radio uses an antenna that detects the horizontal magnetic component of the signal.
The built-in speaker is mounted to the back of the front of the case with a couple of case melts.
The other electronic components are mostly passive — lots of capacitors, a few inductors, and five color-coded trimpots. All through-hole. It has a lower component count than the Coby radio — I only count about 40 discrete components on the board — but since none of the components are surface-mount, I suspect the bill-of-materials cost is close to the same.
I haven't tried reverse-engineering the schematic from the dissection, but I suspect it's probably fairly feasible to do from these photos. The big black switch is the frequency-band selector.
Again we see that it's possible to ship an electronic device with high component count for under US$10 at retail (the other example being the Coby CX-61 radio.) and that it's possible to do multiband RF communication in that price range too. Beyond that, it's not that interesting. It doesn't even contain any digital electronics.
But I was worried about what one friend had said:
I don't have a lot of experience with it [RF] either but [the] people I know in my lab who build even very simple RF components into their applications end up spending quite a lot of money on the projects.