How much is a bicentennial one dollar silver coin woth?

It depends if it is silver. The vast, vast, vast majority of $1 coins bearing the date of 1776-1976 contain no silver. The only silver ones are those in a mint set that say "Silver" on them. Note that there are uncirculated and proof $1 coins bearing that date that contain no silver even though they may be found in mint packaging.

If your coin is not in mint packaging, first look for an "S" mintmark. If your coin doesn't have an "S" mintmark, it isn't silver. If your coin does have an "S" mintmark, look at the edge, if its brown or red its not silver.