What I do is just make the entire announcement and song as part of a single mp3 file.
To create the announcement, I use the demo version of Cepestral Swifttalker (David voice) with the "Spacetime Echo" effect to give it a stadium announcer's voice effect. I type in "Now batting. Number ___. Firstname Lastname." The program will let you hear what the text-to-speech sounds like, and then when you get it just right, you can download it as an audio file. (You may have to tinker with some names, spelling them phonetically, in order to get the program to pronounce the name correctly).
I then select the song that will be used.
Once I do that, I use a free audio editing program called "Audacity" (1) to trim the walk up song to the part of the song I want and the length of song and (2) import in the walk up announcement -- and then create a single file for the announcement / song.
