Robert, your Luger is a commercial DWM made in the early to mid 1920's for export. I had one in the "n" block that was seemingly made from all new components as I suspect yours is. Some of the DWM commercial Lugers from that period were reportedly made from surplus parts left over from the war or a combination of surplus and new parts. That's not to say that the surplus parts weren't new-old stock.... only that they were made during the war. There are also commercial export pistols made during that time period that were re-worked military guns such as the Erfurt I have in .30 caliber.
The Finnish contract pistols were made by DWM and taken from the same run of production. The one I had was in the (lower case) "L" block. Note that the serial number includes the lower case letter "n" as found on your frame but that the last two numbers of your serial number are stamped UNDER the locking block (take down lever) and side plate in the commercial manner. The serial number is military-style while the placement of the serial numbers is commercial.
As to estimated value, your pistol is thought to be the most common garden-variety Luger ever made and has the least collector interest. That's the not-so-good news. Even so, it's worth much more than you paid and in private sale you'd likely get $700 - $800 for it. If you'll go to Simpson's website at:
http://www.simpsonltd.com/index.htm and click on "Luger Room" and then "DWM Lugers", you'll find half a dozen pistols just like yours for $895. Simpson's generally gets top dollar for their guns and in private sale you'd likely get a little less.
If your estimates of remaining finish and condition are accurate, you made an excellent purchase for $450. I have not been without at least one of that type since 1966 and they are one of my favorite pistols to shoot. I hope you enjoy yours.