My great grandfather gave me his antique violin about thirty years ago when I used to play in school. I recently moved into a very small apartment and must downsize. I want to sell the violin but have no idea what it's worth. There's an old sticker inside the violin that reads: Joh. Bapt. Schweitzer Fecit At Forman Nicronymi Amat Petini 1813. If anyone has any info about this violin I would greatly appreciate it. Thank you.