A 600% return on an investment is still pretty good stick! I know many an investor that would like that return.
its not a 600% return unless you hand reg it, sit on ya bum and do nothing then the phone rings with someone saying i want to buy it NOW and i'll pay the COR.
otherwise its, money that could have been earning interest, time it took to register, time for COR, cost of COR, price negotiation time.
a hand reg then sale under $300 is a loss, i've done a couple but i feel i sent them to good homes
as for "valuate" , a domain/house/car has no value until sold.
tim