Not much for that bike its an old bike and really used up
Nice olde MTB, mid 1980s I'd guess. Maybe get $300 if cleaned and tuned and you patiently wait for the person that has to have that bike.
If brakes are in nice shape, and you clean those up really nice, you can get $50 a pair for those Suntour rollercams if you sell to collectors, so there's a hundred in brakes arms right there.
What rear derailleur you got? and brake levers? and shift levers?
1980ish Free Spirit Sunbird fixed * 1996 Mongoose IBOC Zero-G * 1995ish Park Pre Pro 825 * 1997 KHS Comp * 1990-ish Scapin * Lemond Buenos Aires Triple