The sword may be an 1840 used by the US. I just can't tell much from the photo. In general the North South Trader price guide is the place to go for value.

First you must ID the type of sword it is. Second you must determine and provenance and condition issues. It could wholesale for as low as $100 or top out at auction around $250. Of coarse auctions have fees that cut into the price realized. Email me photos if you want a better ID. I love rusty stuff.

-=john=-