I do not think anyone cares about Sean Broderick's autograph except his bank when he signs checks, mortgages, loans, etc. For an autograph to be worth some monetary figure there must be a demand for it. I have never heard of anyone looking for Sean Broderick's autograph but then that could just be me.
There is one on eBay with a BIN for $15. Not autographed and not sold.
I had a Milwaukee Brewer's program signed by a number of players and did not even make my investment of $3 back. Evidently there are no Milwaukee Brewer fans that will pay money for any memorabilia, even cheap memorabilia.