The BA1404 IC is obsolete and has not been made for about 7 years because it had many complaints of poor performance. So its manufacturer Rohm released a few much better ICs that use a programmable RF frequency synthesizer using a crystal oscillator and a phase-locked-loop.
The Micromitter is a project that uses one of the new ICs and the circuit is used in a kit and in most MP3 to car radio FM stereo transmitter products. It has an attenuator at its RF output to produce legal short range.