Hello and Welcome to Just Answer,
My name is***** am a Personal Property Appraiser and would be happy to assist you with your question.
These old console TV's are seeming to come out of the word work these days. You can find your circa 1956-1957 Magnavox "The Brittany" Black and White console TV in a retail antique shop for anywhere from 200-250USD. Generally people are looking to repurpose the cabinets as opposed to watch the TV's, most times the old tubes have been damaged and can cost an arm and a leg to replace if at all.
If you were selling the vintage console TV yourself in a place like craigslist, you my be looking closer to 80-120USD, with the exterior cabinet still in what appears to be pretty solid shape.
I hope this information was helpful to you today.
Best of luck with your vintage Magnavox Console TV.
Any feedback you can leave for my service would be much appreciated.
Please let me know if you have any difficulties with our rating system.