Tough question, the Remington model 550 is a .22 rifle not a 12 gauge shotgun.
30p
800
100-1000 depending on specifics
300 or so
Model 58 is an automatic not a bolt action
$500 and up, depending on condition
probably around 350.00.
New in the box - $500-600.
About 275 in good condition
50-1000 USD or more depending on specifics
100-300 USD