Strike anywhere matches aren't so common any more, but you can still find them if you look around. Try a big grocery store. They may be illegal in some places, I think I remember hearing something like that once.

They are not such a great idea. Safety matches are called that for a reason. If you drop a box of strike anywhere matches on the ground, the whole box can go up in flames if you're unlucky.

For PSK purposes I think you're best off with lifeboat matches and striking surface in your match safe, if you want to use matches at all. Those flint wheel thingies seem like a better plan to me. They're more nuisance to use, but pretty much foolproof, nothing to use up (within reason) or damage by soaking.