I picked up a pair of them in Germany many years ago. They are great little pistols, but let me recommend one that I think is even better, and fits the bill for the type of carry you want the PPK for.
Take a look at a Polish P-64, it is a 9x18 Makorov, slightly more power than the .380, but not quite to the level of the 9mm. It is a very close copy of the PPK, has a seven round capicity (6 in mag, one in chamber), it will also produce some tight groups at fifty feet. I am not wild about the sights, but they are acceptable. Practice ammo is fairly cheap, and they can be purchased for about $150. I bough a pair of them at a show in Dallas several years ago, gave one to my son, who also loves it.
I have a fairly good collection of pistols, but I often find myself slipping the P-64 in my jeans pocket when I go out. It is small, hides well, and should do the job if needed.
It is worth taking a look at.