Just guessing from the photo, but I assume the slide has been hard chromed.. This would "indicate" to me that the surplus P7 was probably a "B" (or even C) grade import.
It could have been an "A" import, but it seems just from reading the various firearm forums (HKPRO & ParkCitiesTactical) that most folks preferred to buy the B/C's if they planned to have the slide hard chromed.
As to the hard chroming itself, I think it would depend on who did it, and the quality of the job.. A good job might increase the value, potentially, to a buyer, a bad job, not.
The mags are going for roughly $50-60.00 each.. Some time back they were even more, but I think the prices have leveled out now. So figure @ 5 mags you are getting roughly $250.00-$300.00 value in the mags alone. (I have seven).
The tools (carbon scraper/bore brush?) are worth something, just not sure how much that stuff is going for now.
But whether the P7 was an A/B/C grade, IF the internals look good chances are it'll still be shooting just fine long after you have left the scene. These P7's were wayyy overbuilt, and it's very seldom you hear anyone complaining about one breaking.
I originally had 3 "A" grade LSP imports, but sold one to finance an HK P2000sk..
I enjoy the feel of the sk a bit better than the P7, but I'm not selling my other 2 P7's...
There are a few firearms that I think of as "classics", such as the Walther P38 (P1), the Browning HiPower, and I consider the fine HK P7 as one also.
I'm betting if you buy the P7 you WON'T wind up using it for daily cc, altho it does a fine job being so THIN and concealable. But if you enjoy the way it shoots, squeezecocking and all I don't think you'd part with it.
Also, it seems there is always a market for P7's so if you don't pay too much for it to start with then chances are you'll be able to get most, if not all, of your money back should you want to sell it.
Listen to that little voice (unless you are off your meds) and if says "buy", then buy.. If you are having nagging doubts about buying it, I would suggest you hold off.
Just personal opinion, no offense to those who might disagree.
Best Wishes, and good shooting.