Jessica,
You had a pretty good day at the estate sale. That gem pan is a nice find. I believe that is Haussler Variation 8. Variations 1 through 4 have round corners and yours has the scalloped corners. Variation 7 would be the closest to what you have, but it does not have No. 20 cast into the pan like yours does.
The value was pretty high back when gem pans were hot - maybe $500. It is probably only about half that now. Those prices assume that your pan has been cleaned and does not have any damage, like cracks, pitting, or casting defects. With all of those swirls, they are a bugger to clean up, but they look really nice when they have a fresh seasoning on them.
Jeff