P5/P5 Compacts are about 50% bigger in size than the PPK/S. They are thicker, due to the locking block system used, but they are much more comfortable to shoot for extended range periods (over 100 rounds). PP/PPKs start beating your hand pretty good after about 50 rounds (at least for me
P5 Compacts NIB are commanding $850 and up. Earl's has them for $995. You see them pop up on GunsAmerica/GunBroker/Auction Arms occasionally.