From the BU treasurer: In the 13 conventions where BU had a sales table we have sold over $7,700 worth of member books!! Considering all the things we use a table for (gatherine place etc.) this is very good and another reason why the table is valuable to members. We still see a trend that the books that sell the best are the ones where the author works at the table or is present at the con and on panels. So, consider what a couple hours of your time is worth in getting your
material into the hands of eager readers.
Info on BU tables:
http://www.broaduniverse.org/conventions/butable.html