As a broke high school student in the early 90’s, sheet music was hard to come by. There’s the music you get from the school orchestra or youth symphony, but minimal sheet music available at the local library. Today, there is the internet, and the great thing about classical music is that the composers are long dead, which means that almost all of it is out of copyright*.
So now, if you hear a piece and want to look at the score or see a particular instrument’s sheet music, just go to the Internet Music Score Library Project (imslp.org). For an amateur musician, this is heaven!
And for most pieces, if you want to hear them, you can always head over to YouTube.
For example, Rimsky-Korsakov’s Capriccio Espagnol
*Gershwin’s Rhapsody in Blue is still under copyright, and in fact was one of the publicized examples mentioned when congress extended copyrights.