I would say that these days if you find a Carbon Fibre NOS condition for $500 that would be a true bargain. These days it is in the $1000-$2000 range!I reckon anything under $500 is a fair price for one in good nick and with everything included. $500 is actually what I paid for mine.
Actually resin will last a lot longer than 5 years even with daily wear. It's the painted surface that will start showing signs of wear, scuff marks etc.Most likely after 5years with regular usage most resin will deteriorate.