You can get some idea by looking at what Lin has for sale here.
Basically it depends on the size and condition of the glass piece. If you have matching pieces that someone could use for earrings for example, you can get a slightly better price than if you just have one-offs or a mixed bag.
Read the article on "Grading Seaglass" to get an idea of what your collection might be worth. I've found that most of the glass I've collected is too "young" to be jewelry grade glass. But you may have a different result.
