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Where was that sale?
I have been searching thru GunBroker and GunsAmerica and find similar guns selling in the $2K range & up while there have been sales of less models for less.
The auction houses I have searched have some listed with projections from the $1400/$1600 to $2700/$3000 range. The Sauer and Krieghoff guns are premiums. And while I have found examples with what appear to be the same action and pattern I have found none with the same names and markings. Of course the engraving varies widely with most having the four different game scenes on the sides and it would appear that the additional animals on the trigger guard, tang or under side of the receiver may have been upgrades.
I agree that the pawn shops are not a place where you normally find gems they have turned over a few nice pieces at decent prices. This particular guy have yielded a nickel lemon squeezer($285), a Pocket Positive($250) and a 1903 auto($425), but it takes contact & haggling.

 

[Crossfire]

A disclaimer: I have no special expertise. Just a few thoughts.
This is what's called a Hahndrilling (with external hammers). While a few custom makers still make Hahndrillinge, this one is probably pre-WW 1; most makers switched to self-cocking internal systems in the early decades of the 20. century.
The markings are pretty sparse. "Erlangen" is a town in Germany not known for gun manufacture, and I would guess that "Krupp Prima Stahl" just refers to the steel the barrels were made of; by the way, the 16 ga is most likely what Germans call 16/65, which is 5mm shorter than standard 16ga (called 16/70).
I know nothing about US prices for these. You wouldn't get anywhere near $2200 for this in Germany, since it seems to be a no-name brand; I found one on the website of Frankonia, the largest German hunting arms retailer, with the identical caliber combination plus a scope, but no pictures (so hard to compare), and that had sold for 699 Euros, so about $1000. But then that's across the water, and this one's here.

Thanks for the info on Erlangen. I suspected it may be a city but wasn't sure. The one think that bothers me is no identifiable makers info. And I thought the Krupp markings were about the steel/barrel maker. All of the guns I have found on line or in auction catalogs have makers names and that is the ONE thing I have NOT located on this one. On the other hand, I know that many of the finest early American long rifles from the PA gun makers (the PA Dutch from Germany) are unsigned because that was viewed as a sin of vanity and was deliberately omitted.

 

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Just a hunch, but I can't see a German gun maker who uses a mass-produced barrel steel with a rather garish barrel marking being too modest about his name. One place to look if it's accessible would be under the barrels in the area covered by the forearm. Most drillings have the snap latch that allows detaching the forearm and unhooking the barrels. If this one does not, I'm out of ideas.

I know that the chances of some lone Hugonaut gun-maker is a bit of a stretch.
But I try to look at all the angles. The gun really is in nice condition and it's a pattern that has escaped be before but the lack of any ID has been bothering me from the start. I have two German made SxS from the early 20th century and both were easily identified as to the makers and the city. I have a cap lock Jager rifle from the 1840s and that has the maker's name and address. I have removed the forearm and separated the barrels expecting to find something but the only marks found are the proof marks.

 

[Crossfire]

Absalom. that is another point I have learned in reseaching this; 65mm European vs 70mm American.