[size=12]It's much easier to answer the first question. Yes, it is a Griswold-made 947 golfball pan. I have one just like it, and I think that it's the commonest of all the variations of 947, according to the yellow book.
Worth? Boy, I hate to guess. Muffin pans have taken a dive in the deep end since the aforementioned yellow book came out, and whenever I try to take that into account, I still wind up usually guessing high. Condition matters a lot, and from your photos it looks like it might be a tad rough.
I'll toss a number out and take cover; providing that it's not cracked anywhere or warped, $40 to $50 in today's market. But that's to a collector that knows what it is from p/n alone, because I don't think it's marked by name anywhere. At $25, I'd say that, if it's in nice shape, your deal was OK, but not legendary.[/size]