your safest bet is to just look at past auctions and see what domains actually sold for. everyone thinks their domain is better than it is, more valuable than it is and has some retarded idea like "well yeah... but its a great domain for...". if you have the capacity to be honest and realistic with yourself... just search google for domain auction results and look around for similar quality domains.
http://blog.domaintools.com/2007/10/...ction-results/