I have been watching for one that has the three "bumps" on the top structure. That feature makes it sit correctly on the milk glass difusers found on some mid century lamps like my brass and black floor lamp, a gift from my nephew Dave (thanks again Dave).
The shade was in excellent shape, and the price was relatively high. But I never see these locally, and my only other option was to buy online and pay about the same and also have to cover shipping costs. So, I paid the price. I think it was worth it.
Here it is on the lamp. The atomic finial is one I already had, but I think it looks good on there.
By the way, I see that I'm one away from having 200 followers here on the blog, and 75 over on Facebook. I guess it's almost time for a giveaway to celebrate! Stay tuned...