YES! How cheap FM transmitter I found with transmitting frequency (MHz) display and with USB/SD card reader! I never expected that I can get such device in my near city in Nepal!
It costs just Rs.380/- (US$3.8)! It has a remote controller from where we can increase and decrease transmitting frequency, control audio (Next, Prev, Pause), Vol+-, Equilizer etc. The device is called "Car FM transmitter/modulator".
Overall audio is not bad (nice for me)! It has no stereo encoder and no channel separation however it's not mono, it sounds like surround sound. Actually it has fake stereo effect which sounds like audio are circulating around our ears (but not stereo). Audio is very crisp (depends on Equilizer). Frequency stability is amazingly stable! Display is not VERY accurate though. The transmitter is displaying 88.2MHz but my cellphone is getting its signal at 88.1MHz. It's OK because it costs just US$3.8! (probably the designer did not calculate the probable 'stray capacitance' so the transmitted frequency has been drifted).
Input voltage is regulated by 78M05 (SMD) so input voltage is around 7V to 12V. Total current consumption is around 90mA. Transmitting range is around 15 to 20 meter (it has no antenna) but simply I can increase range by adding 30 inch wire as antenna. Or I can add a RF amplifier to it to get hundreds of meters (or KMs) of range!
One of the most Exciting thing is that we can use any type of AC to DC adaptors as power supply like a linear transformer, SMPS however it 'DO NOT' produce any noises generated by 50Hz line noise hum or switching noises from SMPS, Wow!
Inside of the device an IC has been patched in PCB, and 12.000 xtal exist and 'j8' (S9018) transistor has been added as RF booster.