100-400 USD
Although they have been discontinued and a little hard to find they are selling at gunshows, September 2009, for from $400-$500.
Ruger's web site has sn data.
100-1000 depending on specifics
No such model in the Ruger line.
Ruger's website has serial number data on its products.
You can download the manual for the Old Army cap & ball revolver that has loading and cleaning instructions from the Ruger website (see related links) under the customer service heading.
Go to the Ruger website. There is a section to date your 22 by serial number.
Do a search on the "Ruger Old Army User Manual". It is a free download and will answer all your questions.
Ruger website, customer service, historical data- and you need the MODEL of the pistol. Your serial number indicates that your Ruger pistol was made in the year 1976.The ending serial number for that year was 13-48646.
If Ruger's website is up, they have extensive sn data on it.
Ruger has a sn search function on their web site.
Go to Ruger's website. They have a sn look up section.