Once I have answered your question, please press ACCEPT if our conversation is complete as that is the only way I am compensated for the time and research I personally put into your individual question. In the Houston area for this piano you should expect approximately $450-$575 in a private sale-final price being determined by actual condition and regular tuning or lack thereof. That said, there are still folks looking to get one that is in good shape at a reasonable price. The nationwide market is currently flooded with 50+ year old upright pianos of various condition.
This piano will take a pretty good amount of depreciation simply due to the age and size of it. Your upright piano was built in 1956 according to Story and Clark serial number records.