Sailor Pens

I bought a Sailor pen, the medium 1911 one with a music nib for
around $100. The actual pen is plastic, I am guessing the pen part was
like a couple dollars and the actual nib was $100. If so in order to
get another type of nib, would I just buy a whole new pen?

No need to buy an entire new pen. See
http://www.nibs.com/SailorSpecialtyNibs.htm. They can replace your
music nib with another one of your choice, and they may buy your music
nib if you want to make the change permanent.