Contenders have a huge value range due to the unlimited number of options available, determining factors are barrel length, finish and material. Frame type (2 old style versions and the G2) frame material (stainless, blued, high luster blue) extras such as scopes, sights, fluted barrels custom grips, etc. To get a good value I would go to the gunbroker.com website (there is a category for contenders) and compare what you have to what is there, you should be able to get a good value for it there.
Remington did not make a carbine in .44 Magnum caliber. They did chamber the Model 788 rifle in that caliber. Do you have a Ruger carbine in .44 Remington Magnum, or perhaps a Marlin in that caliber? sales@countrygunsmith.net
100-1000 usd
100-550 USD
50-300 USD or so
100-1000 USD or more depending on EXACTLY what you have.
50-100 USD
Professional appraisal
You will need a professional appraisal
100-1000 USD
100-1000 USD depending on specifics
Can't be answered without knowing who made it, condition, finish,etc..
Colt revolver44-40serial6423103