Hmm to add my penny to the discussion. I will say go have look and check it, if it looks and drives good buy it. nothing wrong with all these nonsense cat...
I have seen cat C due to broken windscreen, or even a parking dent. Insurance company nowadays write anything off as is a way to increase everyone's premium and cant be bothered with the high cost of repair from high profile garages which they must use.
having said that there are lots of unrecorded badly damage cars that people pay lots of money to buy and as far as they see hpi clear they are fine.
even though its true that coming to sell it will be cheaper. tel me of any car bought and later sold for more. cars like many stuff will depreciate and i think if you buy a cheap one due to bureaucratic cat. on it, it means it wont depreciate further than the hpi clear ones. BUT ALWAYS DO A GOOD CHECK AND RESEARCH.