Bayard Arms Co was one of many brand names used by the company founded in Belgium by Henri Pieper. Henri and his successors made guns of various grades and values, so it is hard to put a value on one now without a detailed inspection of the gun. Most of the Bayard and related guns were utilitarian - solid, well-designed and well-made, but not real expensive then or now. Also, a lot depends on condition, and "good condition" as you describe it might mean something completely different to you than it means to me.
Most Pieper and Bayard guns are worth a few hundred.
Go to http://www.littlegun.be/arme%20belge/a% ... s%20gb.htm
and scroll down to the several entries for Pieper.