I agree with Bujutsu. Beauty is in the eye of the beholder and in truth *anything* is collectible if you enjoy it.
Many revenue stamp collectors have enjoyed putting together year calendars based upon cancel date and/or stamp type. Has very little market value, but think of the enjoyment one could get out of hunting for the dates you need?
I dabble in the stamps of Indonesia and the South Moluccas... areas that no one in their right mind would collect.
Why? Because it's fun.