F.D.R. United Electric Clock

I inherited this clock from my Grandfather. I've been trying to get an idea how much it is worth from searching online. I have not found a thing on my clock. The reason why is instead of having the boat medallion, it has the presdential seal instead. There is no other clock like this online. I asked my Grandfather if there was any work done on it and he told me no. I would really like to know how much this is worth so I can sell it on eBay. And input anyone has would be great at this point. Thanks.

Fair