I assume this is an old Ithaca? The question didn't identify it sufficiently. Not sure about the "A" in front of the number, but Ithaca serial # 202454 should indicate a Flues/New Ithaca Gun model made in 1910. 410's are much rarer than 12 GA, for instance, so it will be worth more. A lot of the value depends on condition, and of course - if a collector is interested in that specific model. That being said, I suspect it could be worth in the $600-$800 range, based on what I see guns selling for at gunbroker.com. A gun dealer would probably have the Bluebook of Gun Values, and could pin it down more accurately. Good luck.