Flea markets and swap meets are good local options for selling old sheet music, and eBay.com, Amazon.com and Abebooks.com all offer online marketplaces to connect with buyers. Auction houses might be interested in the case of rare or valuable sheet music.
Buyers for old sheet music can include musicians, collectors, music stores and occasionally decorators, as sheet music turned into a framed art object. Most old sheet music isn't considered very valuable. The value should be carefully researched before the seller sets the price. Ultimately, a piece of sheet music's value is set according to whatever a prospective buyer is willing to pay for it.