Record the piece of music, convert the wave to mp3 format. Then send as an attachment. Many ISPs have size restrictions on e-mails but 30 seconds of MP3 music should be about 1MB, depending on the type of music.
Having converted to MP3 you may want to consider reducing the bitrate from the (supposedly) 128 kbps to say, something like 18. The quality will suffer but the size and therefore up- and downloading time will be vastly reduced. You could transfer from WAV to this new bitrate at the same time. A program like MusicMatch would allow you to record the track to your hard drive at whatever bitrate you choose, eliminating the WAV conversion.