Welcome. You are at the right website for Ithaca information.
I am no expert on Ithaca guns. Walt Snyder who has written extensively on them often checks in. The Ithaca sxs guns changed over time. They are known by the model names.
Take a look here.
http://www.doublegunshop.com/dgsnos3.htm The gap between 1906 and 1908 is known as the Minier.
It would really help if you posted at least the serial number. Value requires a lot more information. What type of barrels; damascus, twist or fluid? Does it have extractors or ejectors? Actually pictures would be best.
Pete