Natural attacks cost 1 point while claws cost 2. I understand that this is because claws grants two natural weapon attacks while all the others grant only one, but what if I only want one?
I was making up a race based on the Fiddler crab, which has one claw substantially bigger than the other(technically only in males, but that would kinda suck for a race so I dropped it), and found that I couldn't just buy one.
Another stumbling block was when I wanted to give them multiple small legs instead of the usual two. While the race will be large, I wanted them to be slower than usual, so quadruped was already technically off limits, never mind the restriction an the size of weapons that were available.
Looking over the rules I noticed that quadruped is just Stability and Fast with what appear to be arbitrary size restrictions.
So I just paid 1 point for a single claw, and bought stability and left it at that.