Again, most places want a recording and lyric sheet for submissions, not sheet music. If you are selling the song to accompanists for others to sing, or submitting choir arrangements, sheet music is a must. If you sing the songs that you write, this step can seem insurmountable. For those of us happy to make a living, but unlikely to make a million dollars, from our music, there are fairly simple answers. Many studios are set up to get you and your songs from start to finish.
Locale is a factor here.
In some areas, union scale requirements are high and professionals, often accustomed to recording television or movie scores, require arrangers to print out each instrumental part separately. Unless you have friends with an inroad to studios near you, it may be worth your while to go to Nashville. As with any financial enterprise, competition drives the prices down. The prices may be negotiable depending on how much instrumentation you want or how many songs you have. It is far less expensive than writing out each instrumental part note by note, since all musicians can read from the same chart.