What how much is a 1898 liberty silver eagle dollar worth?

I think you're confusing this coin with a modern silver eagle bullion piece that has an artificial denomination of $1, but is actually sold for its metal content. Up till 1935 the U.S. controlled the price of silver and struck silver coins that were really worth $1 and could be spent in normal commerce*.

From 1878 to 1904 and again in 1921, $1 coins carried a picture of Miss Liberty designed by George Morgan, so they're commonly called Morgan dollars. 1898 is a pretty common date for Morgans. Look on the back to see if there's a letter above the DO in DOLLAR. If not, or if there's a small O, as of 01/2009 its retail value is $16 to $21 depending on how worn it is. If there's an S, its value is $17 to $50.

(*) That distinguishes silver dollars from modern small dollars that are golden in color but are actually made of brass, and are eminently spendable in daily commerce too.