I have a couple PA-63's, I paid $100.00 each through my FFL buddy, both are in fine condition, both are 9X18 makarov caliber but .380 barrels can be purchased and installed, I have heard of some .380 conversions on the market. The interesting thing is, I can and have fired a lot of .380 ammo out of them, the brass suffers but they cycle and group fairly good. With the 9X18 mak ammo the groups are outstanding, I have been reloading my own for a while now, I take 9x19 cases and trim them down to a 9X18. I use mine as CCW guns, I have many other handguns but I like the slim design. They come apart just like a walther ppk, just pull down on the front of the trigger guard, pull the slide back toward you, once all the way back just lift the back of the slide straight up and remove, pull the spring off and you are ready for cleaning.
I would never recommend shooting a caliber other than what is stamped on your gun, but I just wanted to share my experience. Do not try 9X18 in you 9X17 gun, very bad things could happen.