Value depends on a few variables: age, condition of metal and wood, sawed off or original barrel, rifeled or not rifeled, wear of internal parts, whether or not the plug was shortened or out, all original or replaced parts, ect. This question was too general to answer definitively. Always ask questions about a gun before purchace and inspect the entire shotgun before purchase. Do not trust a gun being sold by pawnshop owners or gunshow peddlers. Be aware that they are trying to get rid of those guns to suckers who will buy anything. Used guns are not all bad, but you gotta be real careful about who you get them from and their actual condition. Do not rely on the word of a peddler like those afore mentioned. They do not care if the gun is good or not. Price can vary from person to person, even in a gun show. Good guns can be purchased from them at reasonable prices, but sometimes those bargain prices are a warning. I'd go with a single person that you know, who is the original owner, who did no modifications, that didn't abuse the gun.
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
remington wingmaster 16 gauge
probably around 350.00.
50-1000 USD or more depending on specifics
New in the box - $500-600.
100-300 USD