where are you? here in NY the back-up isn't kel-tec, its the company that tests a round through the gun to include with the new sale (not all manufactures do this and it is law in NY and..Maryland?)
So here, that is the back up.. and they are POPULAR right now.

If you are elsewhere... i don't know. Have you asked the LGS if they can get one, why they have none?

I'm in the Orlando area

Still can't find one

I'm not sure this is going to help you much but two things come to mind; first, Keltec's are made in Cocoa Beach. While you can't just go to the factory and buy one, there may be a local gun shop there that will have some inventory due to being local to the factory. So you might want to check them out. It's not all that far from Orlando to Coca Beach. Second, Shooter's of Jacksonville had some of the PF-9's in stock when I was in there last week. This store does a volume business and usually has inventory when nobody else does. You might want to check them out as well.

B&H in Merritt Island has them