According to the NGC (Numismatic Guaranty Corporation), an 1884 silver Liberty dollar in good condition can be worth anywhere from $20 to $30. For higher grades, the value can increase significantly, with some examples selling for hundreds or even thousands of dollars.
1884 Liberty dollars are not particularly rare. The mintage was 10,501,000, which is relatively high compared to other silver dollars of the period. As such, they are not considered to be particularly valuable, unless in high grades or in excellent mint state condition.