Shell gas roadside display

I grew up looking at this thing everyday in Brooker fl, at Greens grocery. Bought it from owners couple months ago, double sided display over six feet tall. She said they got it in the fifties,there was other sighns on the bottom frame that had been painted over with advertisements for the store she rented out next to her store with out her consent the renters painted over the bottom sighns. You can see them against the wall in the second picture behind the sigh,The yellow shell sighns were on the top,when i took it apart to clean it the Super Shell sighns were found inside the display between the painted over sighns on the bottom, i was shocked they have never even seen the light of day that's why they appear to be brand new.Every one ive talked to has never seen this type of display.Is it rare what is a nos gas sighn of that brand worth?