Not currently produced. Start with your local gun shop.
You have a Lewis or NIG model, built in 1903.
Forearm iron and watertable are the easiest places to obtain this info
$800 to $1000 depending on the condition.
If this is an old side by side it would be a Baker model made in 1886. Serial numbers of Ithaca shotguns for that year were 2448 - 4101.
Made in 1925
The Ithaca side by side 12 gauge serial 188650 was made in 1927.
I have an Ithaca model 100 shotgun . It appraised for $700.
I would say that you have a Ithaca model flues double barrel shotgun that was made in the year 1923,with the serial number that you provided.
If the shotgun is a hammerless double, it is a Baker Model produced in 1899 (per Dixie Gun Works, Ithaca Serialization Guide) That serial should be a 1926 production NID. sales@countrygunsmith.net
That should be a "New Ithaca Double", and if it is in very good condition is probably worth around $500-$600. Monitor www.gunbroker.com to see what comparables are going for now.
The gauge is stamped on the water table by the serial number. It is a Flues model made in 1924.
Try here - http://www.ithacagun.com/e -