All I can say is, WOW. 

I think it sold for so much because it is an extremely rare set in collector's condition... closest to mint you can get with those early gillettes. Single ring for a double ring price?... something like that: I think if a double ring was up for auction in that condition will the shipper and all it would sell for $400+ maybe $500+.
I paid no were near that but today's market is a bit higher. Again I'd have to ask if the whole set matches. I'd have to respectfully disagree that this is the closest to mint you can get. Perhaps the closest thing you've seen is a more appropriate statement.
In the Q/A section of the listing it is said that the serial numbers are matching. Of course I say closest to mint loosely but find me an early 1906 single ring with with a case and shipper like that that. Was the price high? To me, yeah, but I'm sure a serious collector was happy to pay it and it looks like they got a really nice piece.
It is a mint NOS with the numbers on the handle and shipper matching making the set as a whole easily worth the $280.
It is a mint NOS with the numbers on the handle and shipper matching making the set as a whole easily worth the $280.
It depends how you look at it, Since the serial number places the set in 1906, 5 dollars back then was a lot of money. Compared $5 dollars back then to what it would have been worth in 2008 using the following website. Here are the results.
Current data is only available till 2008. In 2008, $5.00 from 1906 is worth:
$123.45 using the Consumer Price Index
$94.09 using the GDP deflator
$268.26 using the value of consumer bundle
$518.48 using the unskilled wage
$652.81 using the nominal GDP per capita
$2,326.51 using the relative share of GDP
Only went for about half of what it was work in Unskilled Wages.
Damn! Just imagine how much 30 dollars would have been back then. ...