Is it a Model 99?
Your gun was manufactured in 1909. There are a few versions that it can be. The 1899-A is a lever action with a 26" round barrel. The 1899-B has a 26" octagon barrel. The 1899-C has a 26" half round, half octagon barrel. The Model 1899-D Military Musket has a 28" barrel and a rack number on the buttplate. The 1899-F is a carbine with a 20" barrel and the 1899-CD is a take-down version with a 26" barrel that can be round, octagon or half and half. The values on the standard 1899 are:
excellent-$1500, very good-$1000, good-$600, fair-$250, poor-$100.
If your gun is one of the other versions, let me know and I will get the values for you.
I hope this helps you,