Well, I decided to take a punt on one of these tame looking efforts from Maplin (Item code A20GQ)
Purchase price was a touch under 15 sovs.
It's about the same size and contour as an iPod and finished in that pearlescent white which as we know, sadly turns its owner into a silhouette as a matter of course.
The first thing that struck me when I powered it up was how limited the interface is. The display is small and basic. Changing frequency is slow and there are absolutely no preset frequencies. Just three buttons to play with.
It sounds OK, fairly low noise floor.
The range is outstanding. Outstandingly limited that is. Using a very sensitive Becker receiver, I had to be within a metre of the aerial to get a reliable signal. There is actually no PA stage in this unit, RF comes straight out of the synth chip with no amplification. This is stated to be at around 100dBµV before the output LPF. That would be around -7dBm into 50 ohms so I recon there's a fair bit getting attenuated in the output filter stage.
Inside is quite a tidy little board which is where my interest began to perk up. Everything is spread out nicely, lots of room to work with on the LCD side and all components are numbered.
It features a Rohm BH1415F 
which is of interest, so it's a keeper and there may be hope for this beast yet.
Rohm have a comprehensive range of all in one FM TX chips with I2C programming. The BH1415 is not only a PLL, but a stereo coder and limiter too.
The NanoTeam is inside the case and on the case !
The case accomodates two AAA batteries and the unit is supplied with a power lead (colour white) which drops 12V down to 3V with a stated maximum curent rating of 150mA. There's a ferrite lump on this lead which would preclude it from acting as part of an antenna system thereby increasing erp.
The unit has a switch mode supply built in based around U5, D2, L10 and C27. This generates a +5v rail and runs continiously when powered from an external supply. The BH1415 requires a minimum of 4V to function correctly.
The unit features an automatic power down mode if audio is not detected for a period of 60 seconds. Defeating this couldn't be easier. See no-shutdown mod.
One really positive thing about this transmitter is that it remembers its previous frequency even if power has been removed from both the DC input and the battery source.
As yet incomplete and in places erroneous schematic from what I've pieced together. Requires Eagle by CadSoft
Download eMana Schematic