With the good close up of the receiver, we can finally see that it is for sure a small ring Mauser (not a 98). You can pull the bolt and you'll find two lugs, and no third lug on the rear of the bolt. Some of these have been converted to other calibers, but it's not really worth it. Leave it as is, shoot 7mm Mauser out of it once in a while, and forget about trying to make money on it.
Many Mauser rifles are worth tons of money, but those rifles are generally civilian sporters done up by Rigby, Gibbs, or one of many very fine German gunsmiths. Check out the current issue of Rifle magazine, it's all about the Mauser brand. There is also a thread right now on this forum where a guy has posted up photos of an early Mauser sporter that might be worth some money. There are some military rifles that are worth money, but those are usually Oberndorf (German made) Mausers, and not contract pieces.
Sorry to rain on your parade, but the rifle is worth keeping for it's own sake, not because of any value motive. It's a good rifle. It's a piece of history.