Ruger's web site has a sn date function
100-350 USD
Ruger uses a model number, such as 0804, but the suggested retail price of a new Super Blackhawk stainless 44 Mag is $829.
There's no way to answer this question without knowing exactly what needs to be fixed.
200-400 USD
100-500
Depends on finish, barrel, condition- ranges from ABOUT $225 for a well used specimen to about $475 for a new-in-box.
50-500 usd
$600 USD
It lets you know that it was made prior to 1973. Often referred to as Old Model Rugers.
Send it back to Ruger.
100-1000 USD
100-500 USD or so